


Alchemist meet Agents

by Fullmetal_Bitch



Series: Alchemists meet Agents [1]
Category: Criminal Minds (US TV), Fullmetal Alchemist - All Media Types
Genre: Al and Hawkeye are there for like a second, Dimension Travel, Ed doesn't understand planes, Ed eats a lot, Ed's a genius, Garcia thinks Ed's adorable, Gen, Morgan doesn't trust Ed at first, Mustang Cares, OC is definitely a dick, She's not wrong, Spencer and Ed are BFF's, There are swear words, Truth's a bit of a dick, dunno if they're possible but whatevs, like seriously, new arrays, the BAU just roll with it
Language: English
Status: Completed
Published: 2018-11-17
Updated: 2018-12-17
Packaged: 2019-08-24 18:22:35
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 14
Words: 41,381
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16645442
Author URL: https://archiveofourown.org/users/Fullmetal_Bitch/pseuds/Fullmetal_Bitch
Summary: Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?Updates will be every couple of days or so





	1. Chapter 1

SSA Hotchner's day started early. Way too early for his liking. He woke up to his phones shrill ringtone and JJ's voice when he eventually answered it. Sighing, he got up, got changed and was at work by 5:30am. Bleary eyed with coffee in hand, he made his way through the bullpen and into his office before heading into his teams meeting room where he was greeted by 6 equally bleary eyed people. Offering a quick good morning and apologies for the early wake up call to his team, he handed the briefing over to JJ before draining the last of his coffee.

"Good morning everyone. We're headed to New York. Four people have been murdered in the last three weeks and the locals have called us in to help after discovering the fourth victim, who was killed only four days after the third." JJ said as Garcia showed them photos of the victims. The team was either watching the screen intently or studying their folders and all of them had surprised expressions on their faces,

"JJ, is this right? All the victims died from blood boiling? Is that even possible?" Morgan asked, looking around the room for an answer to his questions. Reid cleared his throat, effectively getting everyone's attention.

"There are some poisons whose effects can heat blood up but I've never heard of blood being boiled while inside a human being. Also, the autopsy reports say that there are no signs of poison and no signs of ways it could've been injected if they were poisoned. I've never heard or read of anything that can do this." He looked up from his folder to find the team in a mix of shock and worry. Reid was the teams resident genius. If he didn't have an answer for this than what were they up against? Reid then pointed out something even more disturbing. "According to the autopsy report, there were no signs of anything that could explain the blood boiling, or any other type of injury, fatal or otherwise. No pre-mortem bruises, needle marks, signs of struggle, cuts, nothing. The coroner seems to be at a loss as to how the killer was able to kill them, aside from the boiled blood."

"Any connection between the victims?" Prentiss asked without looking up from her folder.

"So far, the only connection is they're all male and around 30." JJ answered after a quick check.

"JJ, whats the time line here?" Rossi asked. JJ flipped through her folder before Garcia beat her to it.

"The first victim was found three weeks ago, the second was found ten days after that, the third was found a week later and the fourth was discovered about four hours ago."

"So the killer is shortening the time between kills. We're gonna have to work quickly on this." Rossi almost sighed as he stood up, the others following his lead.

Hotch sighed and rubbed his face tiredly. "Alright everyone, grab your go-bags. Wheels up in an hour."

* * *

 

_Meanwhile, in Amestris_

Ed woke with a start. He was curled up on a chair in his brother's hospital room. He rubbed his eyes with his flesh hand and glanced at the clock and groaned. It was only 6 in the morning. He grumbled as he stood up and stretched his aching muscles before leaving Al to his sleep and went looking for coffee. He slipped out the door and turned to head to the coffee machine down the hall when he bumped into someone.

"Hey! Watch where you're going, would ya?" He half-yelled as he took a couple of hasty steps back and looked up, only to groan in annoyance as he recognised who he'd bumped into.

"Sorry, Fullmetal. You're so short, I didn't see you there." Mustang smirked at him.

"Watch it, Colonel Bastard. You're lucky Al's asleep in there or I'd put you through that wall for the short comment." Edward said as he pushed past the Colonel. "Anyway, what do you want? It's too early for you to be visiting Al so you must want something from me." The Colonel was surprised at the lack of yelling he'd expected from the short comment but not from Fullmetal's observation. He turned to follow Ed to the coffee machine and helped himself after Ed had finished fixing himself a cup.

"You're correct. There's a mission here in Central that I was hoping you could take. I know you're busy looking after Al" he hastily added as he noticed Ed open his mouth to argue "but we've got a missing alchemist. His house is here in Central but no one has been able to enter since all signs point to his home being protected with Alchemy. I've looked at the arrays but I can't make much sense of it. I was hoping you could simply look over the arrays and maybe figure out how to disarm them so we can go in without getting ourselves killed. You won't even have to leave the hospital." He held out a folder Ed hadn't noticed before. Ed snatched it out of his hands as he made his way over to a nearby table so he could sit and read the folder properly. Mustang gave an internal sigh of relief. He wasn't kidding when he said he couldn't figure it out. He may have gotten some knowledge from the Truth after Father forced him to do human transmutation but he still wasn't anywhere near Ed's level. He sat down opposite Ed and watched him as he studied the arrays and the mans military records. Ed barely noticed Mustang sit down as he read through the info he was given. The alchemist was Thomas Harding, also known as the Boiling Alchemist. His military ID showed him to be tall man with tan skin, brown eyes and brown hair. His specialty was being able to boil any sort of liquid and manipulate it. Ed snorted at the originality of the Alchemists title and moved on to the arrays. It didn't take long for Ed to figure out what their intended use was for and it took him only another few minutes to figure out an array to cancel them out. Flipping one of the pages over to reveal a blank back, Ed held his hand out to Mustang who, without any prompting, handed Ed a pen. Twenty seconds later, Ed stood up and handed Mustang the array and the folder on Harding. Mustang noted the lack of surprise out the fact it had only taken Ed half an hour to read about Harding, figure out his array and create an array to cancel it. He was about to thank him when Ed spoke.

"You made the right call not going into his house. If someone had stepped on those arrays, they would've activated and boiled you alive via your blood. You'll need to place the array I've drawn next to his array then activate it but be careful not to accidentally set his array off when you do. Sick bastard, intending to kill people that way." Ed said disgustedly as stepped around the table to get another cup of coffee when suddenly, everything went white and Ed was face-to-face with the Truth.

"Oh fuck me, seriously? Now? You decide to collect now?" he demanded. Truth merely smiled at Ed when he heard a noise from behind him. Ed whirled around only to face Mustang, who looked a little paler than usual and way more surprised than Ed had ever seen him. Caught between feeling sorry for Mustang and pissed at Truth, Ed turned his attention back to Truth. "Why is he here? This wasn't part of the deal, Truth. I was the only one who owed you a favour as payment. Mustang isn't part of this so send him back." Mustang started at his name and took two quick steps forward so he was standing next to his subordinate. Ed merely glanced at him before looking back at Truth, golden eyes demanding an answer. The Truth simply smiled.

"Well, honestly I wasn't planning on bringing him but this situation requires two Alchemists and with your brother recovering in hospital, Roy here was the only other Alchemist who is strong enough to help you with this task. Of course since he wasn't included in our deal, he isn't obligated to go with you. It is his choice. He can go back, with no repercussions at all. However, if he does than your chances of surviving the task I need you to complete is about 30%. One of your alchemists managed to slip through to another dimension and is killing people over there. Your task is to simply stop him."

"Send Mustang hom-" Ed started to say before he was interrupted.

"I'll go." Mustang said causing Ed to look at him. "I have a suspicion this Alchemist is Thomas Harding." He looked at Truth, who merely smiled. "It's my job to bring him in so I'll go with Ed." Ed looked like he wanted to argue but the Truth cut him off.

"Excellent. Ed, you won't have to worry about your automail over there. I'll keep it functioning. Also your alchemy will work. I'll tell you everything else you need to know when you go through the gate." Said gate opened suddenly and black hands shot towards the two alchemists before dragging them through. The last thing either of them saw was Truth's smile before everything went black.

* * *

 

_In New York_

It had only been a few hours since the briefing and the BAU team were gathered on a soccer field in Central Park, a few metres from where the last victim had been found. The local cops were still combing through the area for evidence but had cleared the field so the BAU could have their impromptu meeting to discuss what they'd found after splitting up to follow up on the coroner, victims family members and the newest scene. Not to anyone's great surprise, none of them found anything new. They were just discussing what their next moves were when the air seemed to crackle around them and a bright light appeared a few metres away from them, in the other direction to the crime scene. Everyone reacted instantly. Guns drawn and spread out so everyone had a clear line of fire on the new threat. The light dissipated to reveal to figures lying on the field, seemingly unconscious. A glance behind him showed Hotch that the local PD hadn't noticed anything weird. Facing the two figures again he motioned silently for his team to circle the newcomers and slowly approached them, eyes peeled for any sign of movement. He was automatically picking up numerous details as he made his cautious approach. Both were male, one had black hair, the other blonde. The black haired man was the older of the two, wore a military uniform of some sort and gloves with red markings on them. The blonde had his hair in a braid, wore a black outfit with a red coat and white gloves and appeared to be in his teens. Hotch's mind was running with wild theories about how they got there when the blonde groaned and opened his eyes. Dazed gold eyes met unfamiliar brown ones. Any confusion the blonde was feeling immediately disappeared as he got on his feet and found himself surrounded by six raised guns. Looking wildly around him, the blonde noticed he was indeed surrounded. A groan finally alerted him to the unconscious man at his feet. Kneeling just as suddenly as he'd risen, the blonde checked the mans vitals while keeping his eyes on as many people as he could. Hotch could see the sigh the kid let out as he found a pulse. Using the back of his hand, the kid tapped his companions face in an effort to wake him. The method seemed to work as the black haired man started to stir. The kid shook his shoulder and muttered something to him that Hotch didn't quite catch. The kid sighed again, this time in annoyance and contemplated the group surrounding him. Everyone looked as perplexed as Hotch felt but they still had their weapons trained on the two strangers. He stayed kneeling next to his companion for a moment but raised his hands in an effort to show he wasn't going to attack, as he looked straight at Hotch as he spoke for the first time.

"What the fuck is your problem? Is this how you people greet newcomers? Could you please put those guns down? Where am I? And who the fuck are you?" He rose to his feet, hands still raised in surrender but he now looked severely pissed. Hotch motioned for everyone to lower their guns but not to holster them and everyone moved back around to stand with Hotch, the kid marking their every move. The kid stood there, tapping a foot impatiently as he waited for answers to his questions. "Well?"

"You're in New York and we are agents with the FBI. Now you answer some questions for us. Who are you and how did you get here?" Hotch answered immediately. The kid seemed confused when he said FBI, as though he didn't know what that was. He opened his mouth to answer but a groan at his feet caught his attention. He tapped his companions face again and told him to get up. His eyes finally flew open and gold met black as the blonde grabbed his arm to help him to his feet. The man looked like he was about to speak when he caught sight of Hotch and his team. He raised his hand, fingers poised to snap when the blonde caught his arm and shook his head. A silent message seemed to pass between the two and the arm was lowered. The actions confused the agents but before they could question it, the blonde spoke.

"I'm Edward Elric and this is Roy Mustang. And how we got here is a rather long and fairly complicated story. Short and least confusing version though? We're from a different country and are here to collect a rogue member of our military who is responsible for some murders committed here. So just stay the fuck out of our way and once we find him, we'll be gone." Mustang rolled his eyes at Edward before taking a step forward and clearing his throat.

"Look, I don't think you guys would be able to understand how we got here. No offense but, like Fullmetal so eloquently said," Edward glared at him and Mustang smirked back. "It's rather complicated and we have a murderer to catch so time is a little critical at the moment." Before either alchemist could move away, Hotch spoke.

"I don't know how you got here but it there's the possibility we might be chasing the same man. If so, why don't we help each other out? You said the man you're chasing was military, right? Can you tell us anything else about him? Anything that could help us catch him before he kills again?" The two men turned to each other and started having a silent conversation before coming to an agreement. Mustang spoke again.

"Assuming he is the same man, I think a joint effort would be a good idea. Fullmetal and I don't know anything about this city or this country for that matter and the man you're chasing is extremely dangerous. The two of us stand a better chance against him than you do. No offense. Do you have somewhere much more private than an open field to talk? The information we have is exceptionally sensitive and probably a little unbelievable on your part." Edward, for his part. didn't look all that convinced this was a good idea however he never voiced his objections, just sulked at the ground while Mustang spoke. Hotch could tell his team had some objections to this but spoke before any of them could voice their opinions.

"You're welcome to come back to the Police department with us. We're set up there temporarily and they'll have a spare room we can use." Morgan looked at him like he was crazy to let two strangers anywhere near the police station but Hotch ignored him. "Also, I believe I need to make some introductions. These are SSAs Morgan, Rossi, Prentiss and Jareau and Dr Reid." He said, pointing to each member of his team as he said their name. Edward and Mustang nodded at each of them, acknowledging each member. "Come on, the cars are this way." He turned as he spoke, his team following quickly while the Amestrians brought up the rear.


	2. Chapter 2

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

It was a very silent and awkward car ride back to the precinct where the BAU had set up. The Amestrians both rode in the same vehicle with Hotch driving and Rossi in the passenger seat. JJ, Reid, Morgan and Prentiss all went in the second vehicle and it was just as silent, everyone formulating their own theories about the strangers and their supposed intentions. Rossi's phone dinged as it received a text, drawing the attention of the three occupants. Rossi caught Hotch's eye and shook his head indicating that it wasn't important and Hotch's attention went back to the road before it was drawn to the sight of the two strangers having a whispered argument in the back.

"Is there something wrong?" Hotch's voice broke the silent tension and startled the alchemists out of their silent, yet furious, argument. Ed leaned forward, as though he was about to ask something and Roy grabbed his shoulder to stop him. Hotch thought that if looks could kill, he'd be arresting the blonde for his companions murder. Roy sighed and withdrew his hand, giving his silent permission while also making his disagreeance with Ed's decision known. The blonde simply rolled his eyes at his superior, turned to Rossi and pointed at the device in his hand.

"What's that?" Rossi and Hotch shared a shocked look and Rossi turned to face the blonde.

"You don't know what this is?" He asked, confusion evident as he held up his cell phone to give the blonde a better look. When Ed shook his head no, Rossi studied him for any indications he was lying for some reason. Seeing none, he decided to humour the boy and started explaining it.

"This is a cell phone. The vast majority of people here have one each, including all of us. The primary use for them is to talk to people anywhere in the world, without having to rely on landlines. You can also send a text message to someone if you want to talk to them without having to call them. You can send the same message to a bunch of people at the same time with a text message. For example, if one of us needs the others to meet them somewhere, we can text everyone a time and place and their phones will ding like mine to let them know. Depending on the phone, you can also look things up on the internet, like motels to stay at or restaurants to eat at. There are a few more uses for them but they're not overly important." Rossi didn't think he'd ever seen so much wonder and shock on two people's faces before. Roy had leaned forward to hear Rossi better during his explanation. Ed's amazed expression quickly changed to one of disbelief.

"There is no way a device that small could be that advanced. I don't believe you. I want proof that it does what you say it does." Rossi thought for a moment before he got an idea. Unlocking his phone, he quickly dialed a number and waited for the person to answer.

"Hey JJ. No, everything's alright here. I want you to do something for me though. I'll explain why when we get to the precinct. Give me a moment." Turning back to the two in the backseat, who now both looked like they couldn't believe Rossi was actually communicating with someone else with his phone, he motioned for them to look out the back window of the SUV. They did and noticed the second car the rest of the team left in. "Okay could you stick your hand out the window and hold up three fingers please?" Ed made a strangled noise, almost like he couldn't believe what he was seeing was actually real when JJ complied with the odd request. Rossi smiled as he thanked JJ and hung up.

"Believe me now?" A slow nod answered his question as a stunned Ed and Roy turned back to face the front. Hotch had to hide the small hint of amusement in his voice when he spoke.

"So you two really didn't know what a cell phone was?" Two quick shakes confirmed they did not. The alchemists turned to each other and started talking quietly again, this time discussing the cell phone. Roy wondered if they'd work in Amestris but Ed was concerned with how advanced everything seemed to be here. He'd assumed that alchemy would be common knowledge since Truth had told them theirs would still work over here but now he wasn't 100% certain. When he voiced his concerns to Roy, the older man was stunned. He hadn't even considered the possibility that the others didn't even know what alchemy was. This raised a few new concerns. Should they reveal their abilities to the team? And tell them about Amestris? Ed didn't know what to do. The BAU members had so far done nothing to either alchemist to suggest they were in danger. They'd reacted to their sudden appearance almost exactly how Roy and his team would have if the situation had been reversed and the BAU had appeared suddenly in Amestris. Then Roy had a sudden thought.

"How were the victims killed?" Not expecting either alchemist to ask anything further until they reached the precinct, it took a second for the question to register.

"They were all killed by their blood being boiled." Hotch answered, glancing at them quickly via the rear-view mirror again.

"Do you know how he managed to do that?" Mustang seemed to be simply curious but Hotch and Rossi both felt that Roy and Ed already knew what they were going to say.

"No. The M.E. couldn't find any signs of a fatal wound on any of them. There's no medical explanation as to how the Unsub managed to boil their blood." Ed swore and Mustang looked pissed at Rossi's answer.

"That fucking prick. He finds himself in another country and decides to kill the locals using his alchemy? That's fucking sick." Ed looked extremely ropeable and Roy shot him a disproving look while also looking sympathetic somehow. "What? We'll have to explain absolutely everything to them now thanks to that bastard." Ed shot Roy a look that found both Hotch and Rossi glad they weren't on the receiving end of but Mustang didn't even flinch when he met the blonde's angry stare.

"I know that, Fullmetal. And I'm as pissed off as you are that he's using his abilities over here in that way but you can't solve anything by getting all worked up here. Calm down and wait to go on a rant until we've explained everything to these guys, okay?" Ed stared at him for another few seconds before sitting back and nodding in agreement. Before either agent could ask anything, they arrived at the local Police precinct. Once everyone had climbed out of the cars, Hotch lead them all inside. Everyone could feel the anger rolling off of Ed but, after Hotch shook his head at them, decided the reason for the blondes anger could wait until they were somewhere more private. They all went into an empty room and sat down, waiting for Hotch to speak to the lead detective to request absolute privacy before he joined them. Once he checked everyone was there and comfortable, he turned to the two newcomers.

"So, before we explain everything we know about this case with you two, we would appreciate it if you could explain everything you know. From your reaction in the car, Mr Elric-

"Don't call me that. It's Ed or Edward." The blonde interrupted, causing Roy to hit him on the shoulder for the interruption.

"My apologies, Edward. As I was saying, you seem to know how our Unsub is killing these people. And you mentioned something about alchemy, Mr Mustang. I must admit that I'm not familiar with the term." Hotch watched them as he waited for answers. Both men exchanged a look before Edward sighed.

"Look, like we said earlier, it's a really long and complicated story. We will tell you but keep the interruptions to a minimum. Agreed?" He waited until everyone nodded before continuing. "We aren't exactly from around here. And by 'here' I mean this planet. Dimension? I don't know but the point is that we were transported here by Truth. We live in a country called Amestris, where we are both members of the military." Morgan opened his mouth to ask something but a pointed look from Ed made him shut it again. "Mustang here is a Colonel and I'm technically a Major but don't bother calling me by my rank, I don't care about it. Mustang does though." Ed smirked, ignoring the glare Mustang shot him. "Anyway, we are both also State Alchemist. Now Alchemy is the study of equivalent exchange. Using an array, in most people's cases, you can transmute one thing into another, however certain laws must be taken into consideration. But I'll explain those later. Now, I owed Truth a favour and Mustang here unfortunately got caught in Truth calling that favour in. Basically, a rogue alchemist is on the loose here in your city and it's our job to track the bastard and haul his arse back to Central. Alive is preferable so that he can answer for his crimes over there however his death wouldn't be a total disappointment. His ability is to transmute any liquid to boiling point and to manipulate that liquid. He is using his alchemy to kill people by boiling their blood. That's why I was so angry in the car, I believe that alchemy should never be used like that. It should always be used to help people. Never to kill." Ed lent back in his chair while he and Roy waited patiently for the BAU members to pick their bottom jaws off of the floor. It took ten minutes for the first member to recover enough to talk.

"That's not possible. What you're basically saying is he killed someone with  _magic_." Morgan said, disbelief written all over his face and voice. Ed shook his head

"No, he's using alchemy. It's not magic. It's science. There's a difference." That drew Reid's attention to him and he spoke.

"Look, what you've just told us is something we've never even heard of. I mean, I've only read about alchemy in fantasy novels and old textbooks from hundreds of years ago. You must realise how insane all of this sounds." A look was exchanged between Ed and Roy and a decision was reached. Ed stood up and all eyes turned to him.

"So how about a small demonstration?"

"So long as your demonstration doesn't cause the building to collapse on us, Fullmetal." Roy smirked.

"Oh fucking bring it, Colonel Pyro." Ed shot back before clapping his hands together and pressing them down on the wooden table in front of him. Drawing his hands away, a small wooden dagger followed suit, leaving a decent crater in its wake. Ed grasped the handle and smiled at the BAU team, showing them the (not so) artistically designed knife.

"Wow, Fullmetal. Glad to see you still don't have an artistic eye." Roy chuckled slightly, partly at the noises and looks the agents made.

"Shut your face, Bastard, or I'll show you how well this knife works." Ed snarled back. He laid the knife on the table. "There's your proof." The team stared at the dagger for a few more seconds before Ed suddenly found himself being asked dozens of questions all at once. Holding a hand up to stop the barrage, he pointed to Reid and indicated he could speak.

"How is that even possible?" Roy groaned as he saw the glint in Ed's eye. He knew the boy loved explaining how alchemy worked to others. Ed immediately picked up on it.

"Didn't I just tell you to shut it, Mustang? Now, alchemy works on a couple of basic rules. You cannot create something without giving something in return. Do you see the crater in the table where I placed my hands?" Six heads nodded confirmation. "That shows the amount of material I used to create the dagger. If I'd made it bigger, I'd have used more material thus creating a larger crater. Are you with me so far?" Six more nods. "Excellent. Another basic principle is that you can't change the nature of the material you use. For example, I couldn't have made that dagger from the wood and changed it to iron. I could only make a wooden dagger from the desk since it's primary material is wood. Still following?" Another six nods. "Sweet. Another basic principle is that you can't use more material than what you've got available. For example, I can't take a glass of water and transmute it into a ten metre ice sculpture. I can only use the amount of water in that glass. That is called equivalent exchange and it is the rule every alchemist lives by. Does everyone understand?" Six more nods and Ed sighed with relief. At least he wouldn't have to try and dumb it down even more.

"So you can do whatever you want so long as you follow those three principles?" JJ was the one to ask the question. Ed frowned.

"No. There are some rules you must follow in Alchemy. You must be able to understand the science behind it. How it works and all that. There are only two absolute taboos in Alchemy that every single alchemist knows not to mess with. You can't use alchemy to create gold. That would ruin the economy." He paused to take a deep breath and the team noted a fleeting look in his eyes before his gaze hardened again. Mustang placed his hand on Ed's shoulder quickly, just to remind him not to get lost in his nightmares. "The second,and greatest taboo, is using alchemy to resurrect the dead. There is nothing worth the price of human soul and the cost of a failed human transmutation is more than you could realise." Something in his voice made Prentiss decide to change the topic.

"So can anyone do alchemy? Could we?" Ed turned to look at her before he answered.

"No. Not everyone can do alchemy. Most of our country can't do alchemy. You've got to be born with the talent and thirst for knowledge. And I honestly don't know if you guys could do alchemy. It's safer for you, though, if you don't try. If you try to use an array and you don't have the knowledge or talent to use it, the rebound could very well kill you." Ed said, his expression telling them he was deadly serious.

"So why is your alchemist here killing people?" Hotch decided to change the subject back to the case, since that's why they were here in the first place. Ed shrugged one shoulder.

"Because he's a fucking nutbag?"

"Fullmetal." Mustang wearily sighed, like he far too used to Ed's language.

"What? It's true!" Ed said, sounding almost childish. Mustang turned to the group, most of whom had slight amusement on their face.

"I apologise for him. He may be an alchemic prodigy and genius but he never learnt any manners." Ed snarled at him but Morgan, thankfully, interrupted the oncoming rant.

"How old are you exactly? You don't look old enough to be out of school, let alone in the military."

"I'll be 17 soon. And before you ask, I joined the military nearly five years ago." He reluctantly answered, knowing that that question would be one of the next ones asked.

"You joined your military when you were 12?" Morgan couldn't keep the shock out of his voice and it was clearly evident on everyone's faces. Ed's expression hardened as he held his head up.

"Yup. I'm not telling you why, before you ask. It's none of your business." Mustang's expression softened as Ed sat back down. Rossi decided to break the silence by asking Hotch's original question.

"So why do you think your alchemist is killing Americans?" Mustang shrugged.

"I'm not sure. I was actually assigned a case pertaining to him today. His name is Thomas Harding, the Boiling Alchemist. He disappeared nearly a month ago. His commanding officer never noticed he was gone until two days ago. After trying to locate him himself, he finally put in a missing persons report for Harding. You see, three months ago, Fullmetal, myself and a few others managed to defeat someone whose aim was to wipe out the entire country to gain god-like powers. Fullmetal was the one to eventually put a stop to him. Since then, our government and the country have been struggling to get things running smoothly again. Harding's CO had sent him out on a mission six weeks ago and Harding was supposed to report back three weeks ago. His CO never noticed because of the massive clean up and organisation going on over at Central Headquarters. The report landed on my desk because soldiers had gone to Harding's house and discovered alchemic traps set. I was the only State Alchemist available at the time and his CO figured I'd be able to handle the traps."

"Yeah, then you turned up at Al's hospital room to beg me for help." Ed snickered.

"I did not beg you for help, shrimp." Ed growled but stayed silent as Mustang continued. "Anyway, I didn't know much about cancelling out Harding's alchemy without accidentally triggering the traps so I had Fullmetal look them over. Like I said before, the kid's an alchemic genius. He was able to come up with an array to cancel Hardings without causing a worse reaction." The team picked up on the proud tone Roy's voice took but Ed's lack of reaction suggested he didn't.

"So how come you're here? Did you use alchemy to track him and come over to our world?" Hotch inquired. Ed answered before Roy had the chance.

"No. I'd owed Truth a favour for it helping me keep a promise to the person I hurt the most. It called in that favour and sent us over here to get Harding back."

"Truth?" Hotch wisely decided to focus on the least personal thing Ed just said.

"Yeah, I guess it'd be best described as the alchemic god. Although, Truth is more of an arsehole than it is a god." Mustang struggled to hold back a snort at Ed's description and at the BAU's faces. They almost looked like they were expecting Ed to be struck by lightning.

"Moving back to the case, what can you tell us about Harding's crimes?" Mustang asked as soon as he got his laughter under control. He could already tell that it was going to be fun case, watching the Americans get used to Fullmetal.


	3. Chapter 3

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

20 minutes later, Edward and Roy had the verbal low-down on the four murders. Edward was extremely pissed to discover there was absolutely no feasible explanation, other than alchemy, for how the victims died. When the team expressed their displeasure at not being able to find a connection between their victims, other than their gender and that they were all aged between 28 and 33, Edward immediately perked up. He'd always loved a challenge and this certainly sounded very challenging.

"Can I look at everything you've got on the victims? I might be able to spot something you missed." Reid immediately handed over the files on the victims and sat down next to the young alchemist. When Ed raised a questioning brow at Reid, he simply replied.

"I might need to explain some things to you that you might not understand. Like the cell phone." Ed gave a nod, indicating his acceptance and turned his attention to the victims files. However, his attention never made it beyond the photos pinned to the fronts of each folder.

"Holy shit." He gasped disbelievingly. "Mustang, come and look at this." He placed the photos side by side next to him so Mustang had a better view. His face had disbelief all over it as soon as he saw what Edward had obviously noticed.

"What? What is it?" Hotch immediately asked as he moved to Edwards other side.

"No wonder they never made a connection. Only we could've or at least someone who'd been in the military long enough to have meet most of them." Ed explained while Mustang nodded his agreement.

"It makes sense. Harding had been very unpopular among the others. You wouldn't have realised, Ed. You were away on missions and dealing with Father most of your military life. These four especially had a major problem with him. They'd all complained several times. It eventually caught the notice of General Grumman and he was about to kick him out but Promised Day arrived and then we needed all hand on deck dealing with the aftermath."

"So, what? He's taking out his revenge here? On these people?" Ed asked disgustedly. He was a big believer of punching the real problem whenever possible, instead of using scapegoats.

Morgan thumped his fists on the table, very effectively gaining the Alchemists attention.

"What is going on? What did you figure out?" Hotch asked before Morgan could, albeit less politely.

"Sorry, we kind of forgot we had an audience. Anyway, we know why Harding targeted these four men." Mustang started explaining. "As we said before, there's a military branch for people who can use alchemy. They, and we, are called State Alchemists. Harding is one, which you already know. These four men could be the identical twins to four of our State Alchemists. As you probably gathered from what I told Ed, Harding isn't popular among any of our alchemists. I certainly don't enjoy working with him and as far as I know, Fullmetal never met him, right?" He looked at Ed, who nodded. "These men have different names and lives but they look identical to our alchemists. I think Harding ran into the first victim by chance and killed him, thinking that he was the Amestrian version." Mustang finished explaining but Edward interrupted before the team could say anything.

"It makes sense. I mean, I never thought about it until I saw those photos but I haven't been stuck in a parallel universe for nearly a month with no federal agents acting as my guide. The first thing he probably did was freak out at the difference. Then check his alchemy to see if it worked and then he may have either started to try and figure out a way home or tried to make himself at home here. Like Mustang said, it may have been purely coincidental that he ran into victim one. He probably thought another alchemist figured out how to get here and was coming after him, especially since Mustang said that Harding and the other alchemists didn't get along. I bet if we looked, we'd probably find doubles of everyone back home."

"Okay but how do you know what he'd do once he got here?" Hotch asked, trying to quell the suspicion from his voice.

"Because, aside from the killing part, it's exactly what I would've done in his position." Hotch could tell from the way the boy spoke, he'd been unsuccessful. Mustang obviously noticed as well so he decided to stop trying to hide it.

"How do we know that the second we find this guy, you won't join him? He is, after all, a fellow alchemist and countrymen of yours." Everyone watching the trio visibly flinched at the anger in Ed's voice when he answered.

"Because that man is a disgusting example of our country! He uses alchemy to kill! And its not like he was ordered or blackmailed into doing it. He chose to do it for his own benefit! To take his revenge on people who he thinks wronged him. And since he can't get to them, he's going after the next best thing. It's despicable and it is wrong. The bastard should be caught and he should be punished but you can't do it. No offense, but he's an alchemist. A very skilled alchemist from the looks of his record. Very few other alchemists could go up against him and win, and even fewer non-alchemists. Mustang and I would NEVER join his side. Never." Putting his hand on Fullmetal's shoulder, Mustang stepped forward.

"Fullmetal is right. That man has taken his alchemy and used it for something horrible. Alchemy is a gift that should be used for the good of the country and its people. Using alchemy like this is, well it's simply wrong. Fullmetal was also correct in saying that you will definitely need our help in this. I'm an expert in long-range alchemy, while Harding is more close-range. Fullmetal is brilliant at all types and almost unbeatable in hand-to-hand combat. For you guys to even be able to get close enough to arrest him, someone would have to get up close and personal with him to destroy his array. You must understand, Harding is our responsibility. We knew he was dangerous in Amestris and now he's here in your country where you don't understand his weapon of choice. We are not only capable of catching him but we are also your best and only hope of doing so." Mustang looked around the room as he spoke, his black eyes carefully watching everyone's reactions to what he said. Edward had calmed down enough that he wasn't likely to run across the room to punch anyone so Roy removed his hand from his shoulder. The BAU were watching the alchemists equally closely. Everyone in the room seemed to reach the same conclusion.  _We can't fully trust them but we need their help to catch this guy._

"I'm sorry but I need to discuss this with my team before we decide whether or not to let you in on this case." Hotch sounded apologetic but Mustang still had a feeling that Hotch didn't trust them completely. Which, he thought to himself, was completely understandable. He didn't trust them all completely and he doubted Fullmetal did as well. Mustang sat and watched the BAU team in the corner while Edward turned his attention back to the files in front of him. There were a few things he didn't understand in the files but he understood enough to know that there was definitely no reason for Harding to have killed them, except for their likeliness to the alchemists. Lost as he was in his reading, he didn't notice someone was beside him until they sat down in the chair next to him. Startled, he looked up and saw Reid next to him again.

"Sorry, did I scare you?" Ed frowned.

"No, you just surprised me. What do you want?"

"Same thing as before. Was there anything in the files you want me to explain?" Ed studied him for a moment. Reid genuinely looked like he wanted to help so Edward shrugged and started pointing out a few things like 'computer programmer' and 'football' to Reid. He listened carefully to Reid's explanations and tried to absorb everything he was being told. He saw Mustang walk over to Morgan, Hotch and Rossi and start talking to them but he couldn't hear what they were saying.

"Was there more that you needed help with?" Reid's question brought his attention back to the files and he shook his head.

"No, I think that was everything. Thanks for your help." Edward smiled at him and he saw Reid relax a little before looking a little nervous. He frowned. "What's wrong?" He saw Reid hesitate before answering.

"Would it be okay if I ask you some questions about your country and your alchemy?" He asked really quickly, as though afraid the question would offend Edward. Ed hesitated but decided it would be okay. Reid did explain things about his country to him so it'd be equivalent exchange.

"Okay but I'm not answering anything that I don't want to. Okay?" Reid nodded in agreement and started asking things about Amestris, its history and other countries. Ed answered him as best he could but his country's history had never excited him beyond the alchemy part. JJ and Prentiss eventually joined Reid and Edward, obviously curious about him as well. It wasn't until the alchemy questions got started that Reid, Prentiss and JJ noticed Edward perk up in his answers. Obviously, alchemy was one of his favourite things to talk about. They even managed to ask some personal questions that Edward happily answered. Things like if he had any siblings, what he liked, what he didn't like. But once they asked about his parents, his demeanor completely changed. His voice grew hard and his eyes looked haunted. They noticed Mustang stiffen when they asked the question. He knew that was a sore subject with Edward and was listening carefully in case they got too personal.

"They're dead. Mum died when I was nine. Hohenheim disappeared when I was four. Didn't turn up again until six months ago. He died three months ago." JJ was the only one to say anything.

"I'm so sorry, Ed. That must've been awful, you and your brother growing up with no parents. I can't imagine being in that position." Ed shrugged.

"Was fine. We had Granny Pinako and Winry. They looked after us for a couple of years. Then we found an alchemy teacher. She took us in while we trained under her. We went back home then-" He visibly shook himself, suddenly aware of what he was saying. "Then we went back to Granny. I joined the military at 12 so Al and I were fine after that." He finished, rather quickly. The three listening to him knew there was something else but knew they'd never get him to tell so they left it.

"Winry and Granny sound nice. Were they related to you?" Prentiss asked. Mustang relaxed, knowing they weren't going to press the issue.

"No. Winry is my childhood friend. Granny is her grandmother. She raised Winry when her parents died in the war. They're automail technicians, best in the country." He said proudly.

"Automail?" Reid asked, confused.

"You don't have automail here?" Edward was confused as well. This world seemed so advanced, he figured they'd have amazing automail here. When Reid, JJ and Prentiss all shook their heads, he frowned. "Okay so what do you guys call this?" He asked, removing his glove to show his automail hand, flexing it as he did. All three let out shocked gasps. Reid leaned closer to it.

"We have nothing like that over here. This is automail? What's it for?" He asked, staring at it intently.

"It's automail. A prosthetic limb. I lost my right arm and half my left leg in an accident when I was 11. What to you guys do when you lose a limb, if you don't have automail?"

"We have prosthesis but nothing as advanced as this. How are you able to move it so well? It's almost like a real limb!" At this stage, Mustang, Morgan, Hotch and Rossi had all finished talking about whatever they were talking about and had turned to pay attention to Edward and the others. Edward paid them no attention as he answered Reid.

"Well, it uses electrical impulses to move, just like a real limb. It attaches to my nerves via a port that's installed." Edward explained. "Essentially, it is my real arm except for the fact it's made of steel and I can't feel anything I touch. And I can't feel it if somethings touches that arm. For example, if you were to place your hand on that arm I wouldn't feel it. I'd have to see your hand on my arm for me to register you're even touching it. And if I'm holding onto something with it, you wouldn't be able to get it out of my grip. The automail responds to my nerve impulses. No amount of outside force can break my grip, which is awesome if I want to keep something from someone else. There are a few downsides to automail so it's not as fantastic as it seems." Reid nodded while Edward talked, absorbing everything he said.

"What are the downsides to it, if you don't mind me asking?" Reid asked a little hesitantly. He liked talking to Edward so he was trying hard not to ask the boy anything too personal.

"It's fine. With automail, I have to be extremely careful in extreme temperatures. With the metal literally attached to my skin, I get frostbite or burns in those areas really easy, if I'm not careful. The automail needs a mechanic to check it out every couple of years, or more if you damage it. Depending on where you get it and who originally installed it, that might mean travelling far. Mechanics tend to be very protective of their work and don't like other mechanics to work on their automail. After all, every mechanic has their own style and if you did go to a mechanic who wasn't familiar with their work, they could make it worse. Also, automail surgery is extremely painful and you have to be awake for it. And if you break your automail limb or if you grow out of it, the mechanic has to make and reattach a new one. The nerves being reattached hurt just as much as the surgery." Ed explained in the same way one might explain how to make a sandwich, while he put his glove back on. The BAU team were somewhat horrified to hear that answer, especially when they realised Edward had gone through, what seemed to be, extremely painful surgery on two limbs when he was only 11.

"Yeah, another danger is a wrench to your head whenever Miss Rockbell sees her precious automail in ruins after you've broken it yet again, hey Fullmetal?" Mustang smirked as he ruffled Ed's hair, which earned him a glare and Ed smacking his hand away.

"Yeah, yeah. Whatever you reckon, old man. And besides, I haven't ruined this set in over three months!" Edward pointed out, to which Mustang replied with

"That's a record considering I used to have to send you back to Miss Rockbell nearly twice a year for her to replace or fix your limbs."

"Wasn't my fault you sent me after people who decide they'd rather fight than surrender, even when they were clearly outmatched. Or that nutbag Scar was running around trying to pick off State Alchemists and always went after my automail." Edward snarled in response.

"Maybe it would've helped if you didn't pick those fights, Fullmetal." Mustang couldn't help but point out.

"Hey I barely started any of those fights!" Since this fight didn't seem like it was going to end any time soon, Hotch decide to interrupt the two bickering alchemists.

"Since we can't do anything with the new leads you've given us until morning, why don't we head to the motel to get some sleep?" His team murmured their consent and started gathering their go-bags, ready for a good nights rest. Mustang and Edward then realised they had a problem.

"Is there anywhere in this precinct we could sleep?" Mustang asked before the team had chance to leave.

"Why? The hotel we're staying at should have a couple of rooms available." Morgan asked, a little confused.

"I'm sure it does however we have no money to pay for it. I doubt your hotel takes Amestrian currency." Mustang pointed out. JJ spoke quietly to Prentiss, who nodded at whatever she said.

"You can use my room. I'll bunk with Emily." She smiled at the two alchemists.

"Are you sure? We're used to sleeping on couches. We'd be fine here." Mustang asked.

"Of course. You'll need your rest too and trust me, the couches in cop stations are never usually comfortable." Ed looked at Mustang and shrugged. Mustang in turn, smiled at JJ and Prentiss.

"Thank you both. We appreciate it." After JJ and Prentiss assured them it was no problem, the team and the alchemists both hopped back in the cars and headed for the hotel for a decent nights sleep.


	4. Chapter 4

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

The trip to the motel was uneventful and quiet. Everyone was tired and looking forward to sleeping. Edward was especially tired. He hadn't been sleeping well since he'd gotten Al's body back. It was a combination of uncomfortable hospital chairs and nightmares. Ed was no stranger to the nightmares, he had been having them ever since  _that_  night but they'd been getting more frequent and more brutal now that he wasn't constantly on the move. He made the mistake of mentioning it to Al, who had promptly starting interrogating Ed about them.  _How long had he been having them? How often? Had he told anyone? Maybe he should talk to the Colonel about them._  Ed had shot him down as soon as he suggested that. No way was Ed ever going to show Colonel Bastard any sort of weakness. He assured his baby brother that he was fine, he'd managed to always wake himself up before they got bad and that he'd talk to Winry or Granny about them. He knew that Al knew he was lying through his teeth but Al knew that his brother's stubbornness would only get in the way so he left it. Edward was sure the Colonel knew something was up. He wouldn't put it past his baby brother to tell the Colonel while he was visiting and Ed had ducked out for another coffee. So far, the Colonel hadn't said anything outside of what he would expect.  _Was he okay? Maybe he should get more sleep instead of reading all night._  There'd been short jokes thrown in and Edward had snarled back a few choice words but he knew something was different. The Colonel had only ever asked if Edward was okay when it was so unbelievably obvious that he wasn't. Like that time he'd come back from a mission and had broken four ribs and had a deep gash on his arm that had gotten infected. Or when he'd gotten a nasty concussion and slight internal bleeding, causing him to collapse unconscious in the Colonel's office. So he'd figured that he really looked like shit or Al had said something.

One thing he hated about cars was that he always seemed to fall asleep as soon as they were driving. He was fighting against it because there was no way that he was going to fall asleep in front of strangers and risk the possibility of a nightmare. His struggle must've been more noticeable than he realised because JJ turned around after a few minutes and told him it wouldn't be long until they got the hotel. He nodded in acknowledgement and tried to focus on where they were going. Ed was completely oblivious to the slightly concerned look Mustang had given him after JJ had spoken. Edward had been correct, Al had told Mustang about his brother's sleeping problems. While Mustang had looked concerned with what Al told him, he also refused to say anything Edward before the boy had come to him about it. When Al protested, he'd simply said that he couldn't help Ed until Ed wanted help. Not to mention that if Mustang went to Ed, Ed would know Al had told Mustang and that would cause an issue between the two of them. Al had conceded when Mustang had pointed that out. Ed's stubbornness only lasted so long before he eventually asked for help and both of them knew it. It was simply a matter of waiting to see how long it would last.

Both alchemists were pulled abruptly from their thoughts when the car stopped. Jumping out, they both took in their surroundings while waiting for the second car to arrive, which it did a minute later. While they were waiting for the second cars occupants to get their gear out, Edward suddenly stiffened. He started scanning the area around them, searching for whatever made his warning bells go off. This behaviour was not lost on anyone. A nervous tension fell over them group before Mustang broke the silence.

"Fullmetal? What's wrong?"

"Someone's watching us." He hissed, golden eyes still searching. Then suddenly -

"GET DOWN!" He yelled, simultaneously clapping his hand together and slamming them on the ground. Walls rose around the small group, the BAU team having pulled their weapons out and Mustang prepared to snap. And not a moment too soon. They felt something smash into the wall, cracks appearing in the wall, directly in front of where Edward was still crouched. Ed clapped again, turning his automail arm into a blade before signalling for absolute quiet. Everyone practically held their breath while Ed cocked his head, straining to hear anything out of the ordinary. His flesh hand was splayed on the ground to try and pick up any vibrations around them but since there was a lot of traffic, both tricks couldn't help him. Sighing, he stood up and clapped his hands twice, once to revert the wall back into the ground and the second to revert his automail back to normal. The agents rose their guns and quickly separated to sweep the area. JJ and Reid stayed behind with the alchemists. Once they'd cleared the immediate area, Morgan turned to Edward.

"What the hell just happened?" Ed bristled at the tone of Morgans voice.

"I just saved all of our arses, that's what just happened." Noticing Edward was starting to get defensive, Rossi spoke.

"I think what Morgan was trying to ask was how you knew." Edward didn't completely relax but he certainly wasn't as likely to close up on them. Sighing, he replied.

"I knew someone was watching us because I could feel it. I've had issues with a group stalking me back home so I kinda developed a sixth sense. And I knew we were going to be attacked because because I could feel the alchemic energy being released. When I passed through the gate to get here, I made sure I got some knowledge out of it first. I guess that was some of what I picked up." Even Mustang looked a little stunned.

"Wait, you picked up more knowledge from the gate? I didn't get anything." He almost sounded a little jealous.

"Yeah, well, maybe Truth likes me more." Edward shot at him. "I've through the gate more than almost anyone. I've learnt how to absorb as much knowledge during each pass as I possibly can. Truth owes me that much, at least." Mustang couldn't really argue with that. Not counting last time, he'd only been through once and he'd been forced too. He'd gained knowledge but he was still far behind the Elrics.

"That still doesn't explain how you knew it was an alchemist that was watching us. How'd you know it simply wasn't someone who was curious?" Hotch asked. Edward fidgeted a little.

"Because I could sense his alchemy. Or rather, his alchemic energy. It was Harding, in case anyone was curious. It wasn't a separate alchemist. And yes, before you ask, Mustang. He must've gained knowledge from Truth too. The alchemy he used certainly wasn't his normal alchemy." Edward didn't sound overly confident in his theory, something Mustang noticed and planned to ask him about later.

"What do you mean? He has different alchemy now?" Hotch asked, a little disbelief in his voice but who could blame him?

"Yes and no. His best alchemy is still his boiling alchemy but he does obviously has more arrays for different alchemy at his disposal now. He didn't clap like I do, so I think he still has to draw his arrays. If we head over there" he pointed to an alleyway across the street and too their left, "I could tell you what alchemy he used." Hotch nodded and indicated that Ed should lead the way. Once there, Ed and Mustang spotted the array quickly. Harding had obviously left quickly because he didn't destroy the array. Edward and Mustang recognised it rather quickly.

"It's a simple earth array. He probably used it to form a large rock and throw it at us." Mustang said. They looked across the street and saw it did have a perfect view of where they were standing. With the shadows and the fact that they were tired, it would've been easy to go unnoticed if it hadn't of been for Edward. A sudden yawn and curse word drew their attention back to the blonde. He looked even more tired than he had before. He swore again.

"Mustang, do me a favour. Do some alchemy." Mustang raised an eyebrow at the request.

"And why am I doing that?"

"Because I'm fucking tired. More tired than I should be after using an array that simple." He snapped back. "I want to know if it's just me or if our alchemy is different here." Mustang decided it would be much easier to simply placate the blonde, rather than irritate him further by arguing. Moving further into the alley, Mustang snapped his fingers and stream of fire flew from his fingers before harmlessly dispersing further up. Letting his hand drop back to his side, he noted that he was feeling significantly more tired than before. Turning to the blonde, he told him so. Edward looked triumphant.

"I knew it. It must be because they don't actively use alchemy here. We're relying more on our internal energy than what we'd use back home. We'll have to be careful and get lots of rest to refuel our supply." Mustang frowned. He'd figured that once they ran out of alchemic energy, that'd be it. They'd have to depend on their combat skills more than alchemy.

"So, wait. We'd still be able to do alchemy here once we run out of our internal stores?"

"Obviously. There is alchemic energy around us. Not much, probably a quarter of what we'd normally have back in Amestris. So long as we don't use our alchemy for unnecessary things and we get plenty of rest, we should be fine for when we finally catch up to Harding." Mustang nodded his understanding.

"So you guys can't use alchemy to help us find Harding now?" Prentiss asked. Both alchemists had almost forgotten the team were still there. Edward frowned as he tried to think of a way to explain it simply.

"No, we can still use our alchemy. We've just got to be careful of how much we use and how often. Obviously, we internalise our alchemy energy. That's how we can activate our arrays. However, we draw in our alchemic energy from something else. Scientists back home can't agree on what powers alchemy. Some think it's the tectonic plates, some believe it's the planets life force, some think there's a special layer in the planet that supplies it to those who are born with the ability to use alchemy. Whatever it is, it's obviously weaker here. Probably since no one uses alchemy here. We'd still get tired if we used a lot of alchemy in a short amount of time at home but here, even the simplest arrays use twice as much energy as they should. We're still drawing in alchemy energy from outside but we're doing so slowly. So long as we are careful, we'll be able to help. Besides, I've got a few more new tricks up my sleeve I wanna test out on Harding." Edward grinned. "But right now, the most pressing issue is sleep. I don't know about you lot but I'm gonna fall over soon." His statement was emphasised with a yawn. Ten minutes later, they'd bid each other good night and were in their hotel rooms. Mustang and Ed looked around at their home away from home. There were two single beds, which they'd silently thanked Truth for. Edward kicked off his shoes and collapsed on the closest bed. Mustang made a face at the thought of all the grime he was leaving on his sheets.

"Why don't you go for a shower first, Fullmetal?" Ed opened one eye and glared rather ineffectively.

"Why? I can go in the morning."

"Going for a shower might make you sleep more comfortably, if you aren't covered in dirt and whatnot." Mustang pointed out not so tactfully. Ed frowned and sat up. He clapped and placed one hand on his shirt and jackets and the other on his pants. After a brief moment, alchemic light flashed and disappeared, leaving Ed looking a lot cleaner.

"Happy now?" He grumbled before taking his red coat and black jacket off, leaving his shirt and pants on before climbing under his covers. Edward was asleep less than a minute later. Mustang just shook his head. 15 minutes ago, Fullmetal had been saying they needed to use their alchemy only when they have no other choice. He moved to the bathroom to have a shower. Once he emerged, feeling a lot better, he realised he had nothing clean to change in too. Grimacing slightly, he put his boxers, pants and white singlet back on. He washed his dress shirt, socks and military jacket in the shower and hung them over the bathtub to dry overnight. Edward was still fast asleep when he came out of the bathroom. Mustang sat on his bed, drying his hair and studied Fullmetal. He'd never seen the kid sleep, not counting when Mustang checked on him before work during the many times the blonde had been hospitalised. It was like the weight that the kid carried on his shoulders just vanished, leaving him looking younger and more peaceful. Although, this peaceful image was somewhat ruined by the exhaustion lined in his face. Mustang put his towel over a nearby chair and got in bed, switching the light off as he did. The last thing he thought before he fell asleep was that he hoped Edward didn't suffer from any nightmares tonight. The kid really needed the sleep.


	5. Chapter 5

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

Mustang slept like the dead. Fullmetal could've destroyed the building they were in and he was pretty sure he wouldn't have even stirred. However, just because he slept like the dead, that didn't mean he woke feeling completely rested. Apparently, travelling between dimensions takes a lot out of you so when he woke the next morning to someone banging on their door, he was less than impressed. Groaning, he rolled over and pulled the covers off himself. He'd almost forgotten where they were and nearly flipped until he recognised his surroundings. He stood and padded across the floor to the door just so he could make the infernal banging stop. He stole a quick glance at Edward and saw that he was still dead to the world. Apparently he was invulnerable to loud noises when he slept. Mustang envied him. Rubbing his face with one hand and covering a yawn, he opened the door to reveal Reid.

"Good morning, Colonel Mustang. I've come to see if you two were ready to head down to the station so we can start working on the lead you two got us last night." He sounded way too cheery for the morning, in Mustangs opinion.

"Alright. Let me get ready and wake Fullmetal up. You're welcome to come in, if you'd like. Also, you can just call me Mustang or Roy." Leaving the door open, he turned around and made his way over to where the rest of his military garments were. Putting on his dress shirt, he opted to leave the rest of his uniform since he wasn't in Central. Grabbing his shoes and socks, he moved to Ed's bed to wake him. However, something stopped him. Looking back at Reid, who was standing a little awkwardly next to the bathroom door, he asked

"Is it necessary for Fullmetal to come in with us? If I can, I'd prefer to let him sleep for a while longer. From what his brother told me, the kid's been getting little to no sleep the last couple of months. Also, he's less likely to blow things up if he wakes up on his own terms." Reid blanched at that. He couldn't tell if the Colonel was kidding or not.

"Uh I'm not sure. I'd have to go ask Hotch or Rossi. I'll be back in a few minutes." He hurried out the door. Mustang busied himself with getting ready. He'd just finished when Reid came back.

"Hotch said it was fine but he wants me and JJ to stay here with him. That way when he wakes up, we can take him to the station with us." Mustang raised an eyebrow.

"Why the two of you? Surely one would be sufficient?" He queried, although he suspected the answer Reid gave wouldn't be the entire reasoning behind Hotch's decision.

"It's because our cars only seat 5. There are 8 of us." Mustang merely grunted in response. He checked on Edward one last time before letting Reid lead him to where the others were.

"So how come Hotch picked you and Agent Jaraeu to stay here?" Reid looked thoughtful.

"I'm not 100% certain but probably because we seemed to get along with Edward the most yesterday. I mean," he started to talk a bit nervously now "I know we aren't friends or anything like that but I'm really interested in learning more about where you come from and you two seem really interesting and you probably don't trust us a whole lot but -" Mustang cut him off.

"Dr Reid, you seem very trustworthy and Fullmetal obviously gets along with you, Agent Jaraeu and Agent Prentiss. If he didn't, he wouldn't have talked with you guys for very long yesterday. And trust me when I say that Fullmetal getting along with anyone is extremely rare. I've known him since he was 11 and we've only started getting along in the last six months. Now, if you want to keep that trust, let me give you some advice."

"Okay."

"Don't ask about the night he lost his limbs. Don't ask about his father. Don't call him short. Try to avoid offering him milk. Try not to ask him about his reasons for joining the military. And don't ask about why he hasn't been sleeping. Okay?" Reid nodded and they both stopped as they reached the others in the lobby. Morgan was just hanging up his phone. Giving Reid and Mustang a quick smile, he turned to Hotch.

"She's catching the next flight out. She should land before lunch, hopefully." Seeing Mustangs questioning gaze, Hotch elaborated.

"Our technical annalist, Penelope Garcia, will be joining us later today. I need her to run through security cameras and assist the New York camera surveillance team with finding your missing alchemist." Although he wasn't 100% certain what a technical annalist was, he knew he'd find out soon enough so he didn't bother asking. "Reid, JJ, you'll stay here and wait for Major Elric to wake up. Bring him straight to the police station unless I call to say otherwise." Two nods and both agents turned to head back towards the alchemists rooms. Hotch motioned for the rest of them to follow him to the car. Driving away from the hotel, Mustang could only hope that Edward didn't blow the building up when he awoke to Agent Jaraeu and Dr Reid in his room.

* * *

 

Edward grumbled as he slowly woke. The bed didn't feel familiar and the walls weren't the right colour. He didn't really think too much of it since he was used to waking up in unfamiliar places until he heard two faintly familiar voices coming from one corner of the room. But it wasn't until he felt a warm hand on his shoulder and heard a female voice calling his name that he reacted without thinking. Startled, and not fully awake, five seconds passed to find him standing with his automail blade pointed straight at JJ. Reid had been quick to stand up, hand hovering over his gun, eyes darting back and forth between JJ and Edward. JJ, however, simply stood with her hand raised in a placating and submissive gesture. It took another three seconds for Edward to remember everything from the previous day. His eyes widened in shock as he realised he'd almost hurt someone. Quickly clapping his hands, he transmuted his automail back to normal before looking at the floor, shame filling his eyes.

"Miss Jaraeu, I am so sorry. I swear, I didn't mean it." He apologised profusely, clutching his automail arm like he expected it to turn back into a blade again. Reid and JJ both relaxed as soon as soon as Ed had transmuted his arm back to normal. Both of them knew that Edward hadn't meant it. They could see it in his eyes and body language as soon as he realised who they were. But both were concerned for the boy too. What exactly had happened in the teenager's life for that to be his automatic reaction when he wakes up somewhere unfamiliar? JJ took a cautious step forward and calmly spoke.

"It's okay, Edward. It was my fault. I should've realised you would've been a bit disorientated when you woke." JJ smiled at him when he looked up, shock in his eyes at her reaction.

"No, it wasn't your fault. It's just, the last few times I've woken up somewhere unfamiliar with no one I know near me didn't end well. You couldn't have known but I still should've realised who you were a lot quicker. I'm really sorry." He almost jumped out of his skin when JJ placed both hands on his shoulders and looked him in the eye.

"Edward, it's not your fault. Look, I'm not hurt. I promise, I don't blame you." Edward studied her for a few seconds before smiling when he found no signs of lies. "Now how about you go get ready so we can go meet the others at the station?" Edward nodded and she removed her hands so that he could head to the bathroom. JJ and Reid soon heard the shower running and they both sat back down where they were before Ed woke up. They looked at each other and both let out a breath they felt like they'd been holding for hours.

"That was intense." JJ stated. Reid raised a brow at her.

"Intense? Yeah, that's putting it mildly. Poor kid. He must've been through something awful for that to be his reaction to someone waking him. You handled that really well. I don't know what I would've done." Reid said.

"You wouldn't have been in that situation. You did tell me not to wake him like that." JJ reminded him. Reid snorted but didn't answer back. They heard the water stop running and a heavy thunk as Ed climbed out of the shower. Two minutes later, Edward came out dressed but with his hair down.

"I don't suppose either of you have a comb I could borrow?" He asked the two agents. JJ nodded and disappeared to grab it. A minute later she was back and Ed was happily combing out his long hair. With practised ease, he braided and tied it. Thanking JJ, he handed her her comb back before standing, ready to leave when he suddenly remembered something.

"Oh yeah, do either of you have anything I could use to draw on myself with? Something that would last a while?" A little surprised at the odd question, both agents shook their heads.

"We could ask the hotel receptionist for a permanent marker. If they don't have one, the police station should." Reid answered.

"Okay can we stop by the reception desk before we leave than?" Ed asked.

"Sure, shouldn't be a problem. I'll call Hotch to let him know we're on our way while you ask." JJ said, leading both boys out the door and towards the lobby. Once there, Reid lead Edward to the receptionist desk and JJ made her phone call. She hung up just as Edward and Reid started walking back to her, Edward having been successful in acquiring a permanent marker.

"What do you want that for anyway?" Reid asked as they headed out to the car.

"Oh, I figured out an array while I was in the shower. It should help double the amount of alchemic energy we regain while we're here. That way, we'd last longer in a fight and be able to help you more." Edward said as he closed the car door behind him. JJ and Reid looked at him in shock.

"You figured out an array that could do something like that while you were in the shower?" Reid asked, a little disbelievingly.

"Yup. Alchemic prodigy, remember?" He laughed at the looks on their face. Reid looked like he was going to ask something but JJ's phone interrupted him. She quickly answered it and agreed to something before hanging up.

"Hotch asked us to pick up Garcia. Her flight should be landing shortly. Do you want to come with us or would you prefer to go to the police station, Edward?"

"What do you mean by 'flight'? She flew here? How?" Edward was legitimately confused. As far as he knew, humans couldn't fly, not even with Alchemy. JJ made his decision for him and started driving for the airport.

"You don't have planes where you come from?" Reid asked. Edward shook his head.

"What are planes?" Smiling, Reid launched into a full-blown explanation about what planes were and how they worked. It lasted most of the drive. Ed was following but he looked like he didn't believe a word Reid was saying.

"There is no way that that's real. It would be too heavy to fly." Edward stated, crossing his arms after Reid finished his lecture. JJ parked the car and they climbed out.

"Why don't you come look for yourself?" JJ said, leading Ed and Reid into the terminal. Checking the arrivals board, they saw Garcia wasn't due to land for another 15 minutes. Reid shouted them coffee and breakfast from a nearby vendor and they started heading to the check-in terminals to meet Garcia and show Edward the planes. Ed balked at the metal detector.

"What is that?" he whispered to Reid, pointing at it.

"Oh, that's a metal detector. It helps prevent people from smuggling weapons onto the plane." Edward and Reid both realised the problem with Ed going through it at the same time.

"Crap, so how do I go through it? Half of me is metal!" Ed whisper-shouted. JJ quickly thought of a solution, however. After talking to the workers, the metal detector was switched off and the three of them were waved through.

"What did you say to them?" Ed asked in wonder. JJ simply winked at him but said nothing. After arriving at the gate Garcia was due to land at, they all sat down to finish their breakfast. Edward was trying to take in everything at the airport all at once but there were so many people and so much to look at that he felt almost lost.

"Edward, why don't you come and check out the planes?" JJ asked, causing Ed to jump slightly. He nodded and all of them moved to the glass panels that overlooked the airport runways. Edward couldn't believe his eyes. He saw planes taxing towards the runway, planes landing and planes taking off. Reid and JJ laughed at the look of amazement on his face. He reminded them of a kid seeing a theme park for the first time.

"They're real! This is awesome! Can we get a closer look at one?" He sounded like a kid at Christmas.

"I'm sorry, Edward but unless you're booked on a plane, you can't go any closer to them. Even I wouldn't be able to talk anyone into letting us go on the tarmac." JJ said apologetically. Disappointment briefly showed before it was replaced with a smile.

"That's okay, Miss Jareau. I get it." He said.

"Garcia should be landing any minute now." Reid said, checking his watch.

"What's she like?" Edward asked. JJ and Reid both looked at each other before Reid let JJ answer.

"Well, she's one of a kind but I think you two will get along." JJ said, trying to figure out the best way to sum up Garcia. Edward nodded and entertained himself by watching the planes while waiting for Garcia's to land. It didn't take too long before JJ and Reid were greeted by a very colourful and cheerful blonde. Spotting Ed for the first time, she stuck her hand out to introduce herself.

"Hey! I'm Penelope Garcia. You can just call me Garcia."

"Edward Elric, the Fullmetal Alchemist. Feel free to call me Ed or Edward." He said automatically as he shook her hand. She gasped when he grasped her hand and that was when he realised he'd used his automail arm automatically. Snatching his hand back, he shoved it in his coat pocket quicker than they could blink. Garcia's natural inquisitiveness was about to ask for an explanation when JJ cut her off.

"I'm sure Edward will be more willing to answer questions when we're somewhere a bit more private." The look JJ gave Garcia was one that warned her not to push the matter right now. "We better get going or Hotch will wonder where we are."

"Sure. Okay. Anyway, it's really nice to meet you, Ed. Morgan told me about you and your boss, Mustang? He said that you can use something called alchemy?" Garcia asked as they headed out of the airport.

"Mhmm, but he's not my boss. That would imply that I actually listen to him. And yes, we use alchemy but I'm not going to explain it here. Too many people around." He said before she could ask. "What do you do in the FBI? I'm guessing you're not a field agent since you didn't arrive here with the rest of them."

"Nice observation skills. I'm a technical analyst. Basically, I do background checks on suspects, figure out our victims lives and whereabouts, try to find connections between the vics and provide witty humour when the team calls me. I only ever accompany them on cases when I'm needed on site."

"That sounds really cool. You're like our investigative branch and Fuery all rolled into one." Edward was impressed. Garcia would've blushed at the compliment if she knew what Ed was talking about. Edward asked more questions about her job and for explanations on the things she said that he didn't understand. By the time they got in the car, Ed's head was spinning with the new information he'd gathered. Garcia turned to Ed as soon as JJ pulled out onto the road.

"Now it's my turn to ask questions. First off, what's up with your hand? It felt really cold and un-hand-like." Finding her blunt approach a little refreshing, he pulled his glove off to reveal his automail.

"I lost my entire right arm and nearly three quarters my left leg due to a stupid mistake I made when I was 11. This is automail. It's a metal prosthetic that's attached to existing nerves. Which means that it works like a normal limb except I can't feel anything with them." He explained, wiggling his fingers a little. Garcia looked both shocked and amazed when she saw the hand.

"Wow, these are unbelievable! Did you use alchemy to make them?"

"No, my mechanic back home did the surgery and made these herself. She and her grandma run an automail shop. Granny does the surgeries with Winry's help and Winry designs and builds the automail limbs with Granny's help. They're the best in the country." Edward explained. "Automail surgery and attachment is too delicate and painful to be done with alchemy. There are just too many risks doing it that way." Garcia nodded.

"Okay next question. What is alchemy?"

"Simplest explanation? Alchemy is the art of equivalent exchange. Alchemist are able to take one thing and transmute it into something of equivalent value. For example, I can transmute water into ice but not into wood. I can only use the materials I have. Also, I'd only be able to use what I have available to me. So I couldn't make a six metre ice sculpture out of a cup of water. Do you get it?"

"Yeah I think so. Can you show me?" Ed hesitated for a moment but figured a small transmutation wouldn't take up too much energy.

"Sure. Do you have something small, like a piece of paper or something, you don't mind being destroyed?" Garcia immediately rifled through her bags and produced a notepad. Ripping out a piece, she handed it over to Ed, who then sat it on the seat in between them.

"Okay, here goes." Clapping his hands, he placed one on the paper and a blinding light filled the car. When it faded a second later, Edward was holding a tiny paper version of Al's armour in his hand. Garcia's jaw nearly hit the car floor as she reached at to the little figurine.

"This is unreal! It's so detailed, too! Can all alchemists do this?" Edward shook his head.

"No. Most alchemists have a specialty but I'm kind of a genius at alchemy so I can do a whole heap more than Mustang. Also, I don't have to draw out arrays. Like you saw, I simply clap and press my hands to whatever I want to transmute to activate an internal array. Mustang's specialty is fire. He's the only person in Amestris who can use fire alchemy but because he spent his whole life studying one ability, he isn't that good at others. There are alchemists who specialise in air alchemy or growing trees or creating crystals or fixing houses. There's a lot of different ways to use alchemy but most alchemists are like Mustang. They're much more adept at one type and weaker at others. My brother and I are special. We practised alchemy without anyone to teach us from the time we could read until our mother passed away and we found Teacher. She taught us to fight and helped refine and broaden our alchemic knowledge. Al's always beaten me in a physical fight but I'm better at alchemy so it's a fair trade." He laughed.

"Wow, so alchemists are like X-Men? That is so awesome!" Garcia grinned at Edward. Edwards blank look must've told her that he had absolutely no clue what she was going on about.

"You don't know who the X-men are, do you?" Edward confirmed that with a shake of his head. Garcia grinned like a Cheshire cat, which if asked, Edward would swear up and down that it definitely did  _not_  make him nervous one bit.

"Well, my young grasshopper. Let me enrich you in one of the most important parts of our culture. Comic book characters."


	6. Chapter 6

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

It took a long time for their car to finally stop at the police station and Edward was secretly relieved. He liked Garcia, she was really nice and he could tell that she'd never hurt anyone intentionally however there was only so much one could take when it came to discussing pop culture,  _especially_  if that person had no clue what a superhero or comic book even was. Reid and JJ were sympathetic towards Edward as they'd both been through the same lecture, albeit theirs was much shorter since they'd both known the more popular characters. His head swimming with information that he wasn't 100% certain would be even remotely relevant to catching Harding, Edward stepped out of the vehicle with a sigh of relief. Once the others had joined him on the sidewalk, they quickly made their way through to the room the BAU had acquired. Aside from Morgan and Prentiss, everyone else who'd left that morning was in the room, reading over the case files again. While the initial greetings were shared between the team members, Ed made his way to sit next to Mustang and immediately helped himself to some paper the other alchemist had acquired. Ignoring Mustang's half-hearted protest, Ed pulled out the pen he'd borrowed from the hotel receptionist and quickly drew out an array that Mustang had never seen before. Edward passed the finished drawing over, which Mustang immediately accepted and studied.

"Okay, I give. What's this supposed to do?" Mustang queried after a few seconds. Edward snorted, which captured the attention of the agents.

"What's it look like? Come on, Mustang. You're supposed to be intelligent."

"An array to make you taller?" Edward barely held back the urge to punch him in the face.

"Bastard. It's an array I created this morning. Basically, it'll act like a sponge." Realising a better explanation was needed here, he continued. "It's designed to be drawn somewhere on us so that when we activate it, it'll absorb the alchemic energy at a much faster rate than we can in this world. It'll then store that energy in us so we can use it like normal. Basically, when we finally catch up to Harding and he decides he's not going back to Amestris without a fight, we can use this array to replenish our alchemic energy quicker than we can thus we'll not tire as quickly as he would." Mustang's jaw was not the only one to almost hit the floor.

"That's what you thought up this morning?" Reid sounded stunned. By the looks on their faces, so was everyone else.

"Ah, yeah. Alchemic prodigy here. This isn't the first array I've created. Anyway, that's not the only thing I thought up since we got here. I think I figured out a way I can find Harding." Hotch immediately latched onto that statement.

"How?" Edward almost squirmed from the sudden attention he'd gotten from everyone in the room.

"Well, it's just a theory at the moment. I'd need to test it out on a smaller scale first but I think I can send out alchemic waves that would find his location. I'm not sure how I'd receive the information back though, which is partially why I want to do a small scale test first. The other part is because if this rebounds, the backlash from the smaller test probably wouldn't kill me."

"It could work. When it comes to alchemy, no one is more ingenious than Fullmetal. But he's right. A small test would be needed first, on the slim chance his theory is incorrect. But before that happens, what exactly are you exchanging for this?" Mustang's dark eyes locked onto golden ones as he asked.

"It would require huge amounts of energy. For the small scale one, I'd probably feel almost as exhausted as I did yesterday. For the large scale one, I'd probably feel like I'd been fighting all the homunculi plus Father at the same time. It shouldn't kill me. Worst case scenario, I end up sleeping for a couple of days straight." He shrugged casually. He wasn't worried. "Before you argue, Mustang, remember I know my limits better than anyone. This array won't kill me, assuming there's no rebound." He'd seen Mustang's expression and he just knew that Mustang wanted to argue against it.

"Fine. We'll do the small scale test but once we've established the array works as intended, we are going to have a chat about the large scale one." Edward rolled his eyes at the man but Mustang stood his ground.

"Fine, whatever. Hey, by the way, where are Agents Morgan and Prentiss?" He asked Hotch, realising they still weren't back.

"They're chasing up a lead. Harding has been spotted so they went to check it out."

"Oh okay. Have they found anything yet?" Hotch shook his head.

"No, they called not long before you showed up. They found nothing so they're heading back once they've grabbed everyone dinner."

"Oh thank Truth! I'm starving!" Edward exclaimed.

"You're always hungry." Mustang smirked, amusement evident in his voice.

"You try carrying around two metal limbs and going a whole day with no food." Edward shot back. Mustang raised his hands in a mock surrender but the smirk never left his face. Garcia took this opportunity to introduce herself to the second alchemist before Edward knocked him out.

"Hi! I'm Penelope Garcia." She said, extending her hand, which Roy grasped.

"Roy Mustang. Pleased to meet you." He smiled at her before releasing her hand.

"So are you like Ed? You can do alchemy too?"

"Yes. My alchemic specialty is fire. Ed's specialty is making the biggest mess he can." - "HEY!" - "What is it you do for the FBI, Miss Garcia?" Mustang asked, ignoring Ed's interruption and consequent mutterings. Garcia laughed before telling Mustang what she'd told Edward earlier. Mustang had just finished asking a few questions when Morgan and Prentiss walked into the room. Edwards eyes immediately focused on the food the two of them were carrying. Morgan and Prentiss placed the cardboard boxes on the table and flipped them open to reveal four steaming pizzas. Ed's mouth began to water at the smell of them. Once everyone had sat at the table, they all began to eat while discussing Morgan and Prentiss's lead and Ed's newest array and his possible tracking method. Edward, for the main part, didn't talk if he could help it. He wasn't kidding when he said he was starving. Once he was finally sated (one giant pizza later) he went to work on his tracking array. Although he had it in his mind, he was going to draw it out. This helped him find any potential faults in the array beforehand and, in the event of a rebound, it would lessen the injuries he might sustained as opposed to if he activated the array how he usually does. He was focused on his work when Mustang suddenly snatched the paper away from him.

"Oi! Give that back, bastard!" Edward snarled as he turned to face Mustang.

"Pay attention and I will." Mustang pointedly said, one eyebrow raised in an amused way as he nodded in the general direction of Hotch. Confused, Ed turned to face Hotch and realised the agent had been trying to ask him a question.

"Sorry, I get a little too focused sometimes when I'm trying to figure something out. What were you asking me?" Hotch waved his apology off. He knew how it felt to be completely focused on work to the point of blocking everything else out, after all.

"I just wanted you to explain your tracking idea in more detail and to tell us if you need anything for it." Edward nodded before launching into his explanation.

"I don't need anything for this array aside from plenty of rest beforehand and lots of food. Now, I'm not 100% certain what this array will be searching for. It could be focusing on Amestrians, people with large alchemic energy, people who have passed through the Gate or it could be solely tracking whoever I focus on at the time. Until I do the test run, I simply won't know. The only thing I know for certain is it will somehow find him. I couldn't even tell you for certain  _how_  it'll work until I've done the test run. I've never used this type of array before so there are a few uncertainties which is precisely why I'm doing a small scale run with it first. Too much could go wrong if I didn't. And before you ask, I want to do the test run today and all I'll need for that is for Mustang to hide somewhere." While Mustang could figure out why, a couple of the others were a little confused.

"Why would Mustang need to hide?" Hotch asked, looking for the blonde to confirm his suspicions.

"So I can use the array. Mustang is Amestrian, has alchemic energy, been through the Gate and would be the person I'd be focusing to find. He fits all the possible criteria therefore he's the perfect test subject." Having his theory confirmed, Hotch nodded. Satisfied that no more questions were about to be asked, Edward turned to face Mustang.

"No time like the present so get lost, Mustang." Edward said rather bluntly. "Just make sure you stay in the building." Rolling his eyes at Fullmetal's usual eloquence, Mustang stood up to leave before pausing.

"Is there anywhere in this building that's off limits?" He asked the BAU team.

"The only place I can think of is the evidence room and holding cells. Would you like one of us to go with you?" Hotch asked knowing that the local PD sometimes used extra rooms for case related stuff and preferred people who didn't work directly on the case to stay out of them. Mustang thought it over for a couple of seconds before deciding it was better safe than sorry and accepted the offer. Prentiss volunteered to go with Mustang and they left together, looking for a good place to hide from Edward. Meanwhile, Edward got to work carefully sketching the array out onto a brand new piece of paper. He could feel the curiosity and nervous tensions radiating from everyone left in the room but paid absolutely no attention to them. He needed this array to be perfect to minimise the potential risks. Satisfied with his sketch, he placed it in front of himself and finally looked at the others.

"How long has it been since they left?" He wanted to give Mustang and Prentiss plenty of time to find a good spot before he activated the array.

"They've been gone nearly three minutes now." Reid informed him.

"Okay, that should be plenty of time. I'm going to activate the array now. Do not come near me until I say so. Understand?" His tone left no room for argument. After they all acknowledged what he'd said, Edward closed his eyes. Taking a deep breath to calm his nerves, he focused on Mustang and activated the array. The room lit up with blue alchemic light that blinded the agents before settling to a light glow. They all stared at Edward who was standing completely still with one hand still on the array to keep it active. However that's not why they were staring. Ed's eyes were open but instead of shining gold, they were glowing softly with the same alchemic energy as the array was letting off. They all stood there watching Ed for nearly 20 seconds before Edward suddenly gasped. His eyes snapped shut and he took a couple of hasty steps back from the array, ending the transmutation. He was bent over, hands on knees, breathing like he'd just finished running a marathon. The agents automatically stepped forward before remembering Ed's warning and managed to stop themselves. The blonde hadn't given them the all clear yet. Focusing on controlling his breathing like Teacher had taught him, it took Ed another 30 seconds before he straightened and faced the others. A little surprised at the concern on their faces, he smiled reassuringly.

"I'm okay. I overestimated though. I'm not as tired as I was yesterday but I could do with a nap. Mustang and Prentiss are up one level and in a small room that had a coffee machine in it. I'm assuming it was a break room." Edward made the executive decision to sit before he collapsed while JJ quickly called Prentiss to tell her they could come back. Edward folded his arms on the table in front of him and rested his forehead on them while he waited. He knew the agents had questions but he didn't want to be asked twice and, to be honest, he could use the small break to think over the results of the small experiment. Suddenly, there was a hand on his flesh shoulder, shaking him gently. He looked up and was startled to see Mustang knelt next to him.

"You okay?" Mustang's eyes were full of concern, which the blonde was mildly surprised to see.

"I'm fine, Mustang. Just tired. Anyway, was I right? Were you in a room upstairs with a coffee machine in it?" He straightened up, eyes glancing between Mustang and Prentiss. The latter spoke before the former had a chance.

"Can you be more specific, Edward? There are two rooms upstairs that have coffee machines in it." Prentiss asked, almost apologetically. Edward frowned in concentration as he thought back to his results.

"There was a fridge and a couch in there too. And someone had left a coffee mug in the sink." He said, a little uncertain.

"Yes! That's where we were!" Everyone was impressed. They had all haboured a small doubt the array would work. It didn't seem possible or logical. Mustang gave Ed's shoulder a squeeze, which was as good as a compliment in Ed's opinion, before he stood up and sat in the chair next to Edward. Edward had a tired smile on his face and he was secretly surprised it had worked so flawlessly. Hotch was quick to the point after he got over his mild shock and joy the array had worked.

"Can you explain how it works now?" He knew the blonde was tired but he wanted to know.

"It used Mustang's alchemic energy to track him. Basically, I sent out a wave of alchemic energy which created a map in my mind that expanded until I had located someone with alchemic abilities. Mustang showed up bright red when the wave reached him while all of you were simply white. Although, I suspect each alchemist has their own colour. I could sense my own alchemic energy and from what I saw of myself, I was gold. The map wasn't detailed like a photo. It looked more like a blueprint, only with spots of white to mark where the people were and red when it reacted with Mustang's energy. As soon as I sensed Mustang, I stopped the transmutation. But there was a limitation. I could only see everything that was in the same direction I was facing. The wave was only sent out in the direction I was looking, but it wasn't limited to this building. I had started seeing other building next to and behind this one before I stopped transmuting. Which means that when I use it to track Harding, I'd need to know what direction he was heading. I could send out more waves to my left and right without stopping the transmutation; however behind me will always be blind-spot until I adjust the array. The array will always deactivate as soon as my hand moves or lifts off." Hotch nodded as he took in the information.

"So how are you feeling now?" He asked more out of concern than anything else but he still needed to know roughly how much ground the kid could cover in one go without overdoing it.

"I'm still tired but I could've covered a lot more ground before I had to stop." He knew why Hotch had asked but he didn't blame the man. Mustang would've asked for the same reasons had they been back home doing this.

"Good. How much more area do you think you could've covered before you had to stop?" Hotch knew that it sounded like he cared more about the results than the blondes well being but he needed this information, both to make sure they got Harding and that Edward didn't push himself to far. Edward considered his stamina and how he felt now before doing some guesstimating.

"I could probably keep that array active for four minutes before I needed to stop. Five tops." Was his eventual answer. Mustang had bristled slightly at Hotch's questions, even though he knew the man was asking exactly what he himself would've asked. He didn't understand his reaction, just that he felt he needed to protect Edward from it. He only half listened to Fullmetal's response while he tried to figure his feelings out. He was snapped out of his thoughts a few second later when Ed called his name.

"Hey, Mustang, you awake over there?" Edward asked, a little miffed but slightly concerned. Mustang mentally shook his thoughts clear.

"Sorry, what did you want?" Edward's gaze showed some concern but he ignored it, focusing on the blonde's question.

"I asked if you felt anything when I activated the array or before Miss Jareau called Miss Prentiss."

"No. I felt nothing. I didn't know you'd found me until Agent Prentiss told me we could go back." Edward breathed a small sigh of relief.

"Good, hopefully that means Harding won't be tipped off when I use the array to find him." If an alchemist of Mustang's caliber couldn't sense his transmutation, he doubted someone like Harding could. Turning his attention back to the agents, he spoke.

"I'll be right to the array again tomorrow. However, I suggest that we hold off using me until we have a fresh, confirmed lead on Harding's whereabouts. It makes no sense if I activate this array somewhere he is likely to have moved a good distance from."

"I wouldn't have asked you to waste your energy on a sighting that was old or unconfirmed." Hotch informed him, a little irked the teenager had assumed otherwise. Edward simply nodded and yawned abruptly. He hadn't really thought the man would've but he had wanted to make it absolute. Noting the blonde's yawn, Hotch glanced at his watch. It was only 7pm but the alchemist had had a long and exhausting day.

"Edward, Mustang, Morgan, and JJ. You lot can go back to the hotel. Get some dinner and some sleep. We'll take shifts until we get some new leads on Harding's whereabouts. No arguing." He added the last part when he notice Morgan opening his mouth to argue. Morgan shut it and simply nodded, even though he wasn't too happy with the idea. Edward was too tired to argue and Mustang was happy he didn't have to leave Ed's side, especially with the young alchemist as tired as he was. He didn't completely trust the BAU agents to be able to protect Ed if something happened. They all started to walk out, Ed a little wobbly at first, and hopped in the car. One uneventful car ride later, they all hopped out and entered the now familiar hotel. Reaching their floors, they all said goodnight before separating to their individual rooms. Kicking his boots and sock off and removing his jackets in record time, Edward curled up under his blankets before Mustang had even finished removing his own boots and socks. Settling into his own bed, Mustang turned to face the blonde.

"Ed, are you sure you're okay?" Mustang couldn't keep the concern out of his voice as he asked. Edward snapped his eyes back open and locked gazes with the Colonel. He wasn't used to Mustang being this concerned about his well being.

"I'm fine. I just need to sleep. Why are you acting so concerned?" Mustang barely stopped himself from flinching under that golden gaze.

"I've always been concerned about you, Ed. You and your brother. I just couldn't show it back home. People would've considered you one of my weak spots and they would've gone after you to exploit that. As it was, you were always a convenient target for kidnappers." Edward was stunned. He'd never considered that Mustang would've cared and certainly not enough that he was actually protecting them that much. Sitting up a little, he searched Mustang's face for any hints of a lie. He found none.

"You seriously cared about us that much?" He asked softly.

"I still do. I was always worried when you went on missions and I was worse whenever I heard you'd been injured." Mustang answered, completely honest. Edward's gaze softened.

"Thanks, Mustang. I promise I'm fine. I seriously just need sleep and a decent breakfast in the morning and I'll be 100% again." Mustang nodded.

"Get some sleep than, Ed. I'll talk to one of the agents in the morning about getting you breakfast."

"Make sure it's a lot." Edward said as he shuffled back under the blankets, much to Mustang's amusement.

"Don't worry, I know what you're like." Mustang chuckled as he made himself comfortable in his own bed, before turning the light off.

"Thanks. Goodnight, bastard." Edward smiled to himself.

"Night, brat."


	7. Chapter 7

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

When Ed had finally crashed for the night, he'd been hoping that his new transmutation had drained him enough to earn him a good nights rest. As usual, Ed was wrong. He sat straight up in his bed, gasping and covered in sweat. Calming his breathing as much as possible, he started looking around his and Mustang's room. Taking in the now familiar surroundings helped calm him even more. He was no stranger to the nightmares. He'd seen more horrible things than anyone else his age could ever imagine so it was no mystery why he got the nightmares. They were part of his punishment for all the bad stuff he'd done during his quest to get Alphonse his body back, so he had absolutely no regrets.

Even so, sometimes he just wished they'd go away. They were exhausting, both mentally and physically. He was almost always tired which had never been an issue before he succeeded in his quest. He'd always been on the move and almost always in life-threatening situations or on missions for the military. Plus, he'd always had Al to wake him up before his nightmares turned really bad. Once he woke up from them, he'd always been able to go back to a dreamless sleep. But this time he knew he wouldn't be able to go back to sleep. Glancing at Mustang's sleeping form, Ed slipped out of his bed and headed for the bathroom. Back in Amestris, Ed would always read, go for a walk or do both on a sleepless night. Here, though? He didn't have any reading material and going for a walk in an unfamiliar city with a murderer targeting alchemists and/or their lookalikes didn't seem like a brilliant idea. Despite what Mustang thought, Edward didn't always go looking for trouble.

Splashing water on his face, Ed looked at his reflection. He didn't look too exhausted. Sighing, he straightened up as he contemplated what to do now. He couldn't read, going outside without back up was just asking for trouble and he didn't feel like sitting in his bed, alone with his thoughts. His next best option was wondering the hotel, maybe going to the lobby and seeing if there was anything there to entertain him. Decision made. He put on his black pants, socks and red jacket, forgoing his black jacket and shoes, and slipped out of the room. Hands in pockets, he made his way down the dimly lit hallway, trying to muddle his way through his thoughts. He was surprised to find himself suddenly in the lobby. It was still brightly lit and manned by one person. Ed made his way over to the counter and caught the hotel employees attention.

"Hello, Sir. Is everything alright with your room?" The clerk, James according to his name badge, asked. In his experience, no guest came out of his room at 3 in the morning unless there was a problem.

"Hmm? Oh, no. There's no problem with the room. I just can't sleep." Ed almost missed the small sigh of relief the clerk released upon hearing that.

"I'm sorry to hear that, Sir. How may I help?" Guests with sleeping problems weren't uncommon. James just hoped there was an easy solution to this guests problem.

"I was just hoping that you might have any books I could borrow. It doesn't matter what genre. If not, would you have any paper and pencils I could steal? And is there a quiet room somewhere that I could use?" Edward didn't feel like explaining why he was up to Mustang, should the man actually wake up. The clerk didn't look surprised at his requests. Turning his back to his guest, he picked up a small box with a dozen or so books in it. Sliding it along the counter top towards Ed, he explained.

"Sometimes guests leave belongings behind at the end of their stay. These are books that haven't been collected by their owners yet. You're welcome to read them but please return them all when you're done, just in case their owners want them back. Also, there's an empty room just over there that we have for business meetings. You're welcome to use it for as long as you like. We've no meetings scheduled for a few days." Hefting the box into his arms, Ed voiced his thanks to James and headed towards the indicated room. Shifting the box so the weight was being held up solely by his right arm, he opened the door, switched on the lights and closed the door in rapid succession. He plonked the books onto the table and studied his surroundings. There was some sort of white sheet like object hanging on the wall directly opposite the door. There were enough chairs for 10 people to sit around the table, with a couple of extras to the right of the room. The was a weird metal contraption hanging from the roof, pointed towards the white sheet. Ed surmised the door objects were related to one another. There was also a small coffee station on his left. Ed was tempted but he didn't want to risk breaking the machine because he didn't know how to use it properly. Besides, he wasn't tired enough to need coffee to wake him up now he had the books.

Choosing a chair away from the door and windows, a habit he picked up when he was being hunted by the homunculi, he started to sort the books out. There were a few non-fiction books, a couple of romance novels that Ed was never going to touch, a couple of textbooks and a couple of true crime novels. Ed looked at his options and decided to start with the textbooks. A quick glance confirmed they were from different high schools so he hoped they'd be as close to what he normally read as possible. They weren't as detailed as he would've liked but half an hour later he was a bit better versed in some of the history and sciences of this world. He was glad that, so far, Amestris and the other countries hadn't initiated anything on the same scale as the World Wars of this world. Even the Civil War of this country sounded worse than the wars in his world.

Shaking his head at the atrocities committed here, he next moved onto the true crime novels. As he'd hoped, they gave him a better explanation as to how the police here worked. He found that, aside from some technological advances and other minor things, there weren't many differences between how the Amestrian police and the police of this world operated. Granted, this world didn't have alchemy to hinder or help an investigation, present case excluded. The murders in these books always seemed pretty straight forward, however they were still fascinating to read. Much more interesting than boring military mission records, that's for damn sure. Ed took a little more time with these books, making sure he never missed anything that might prove useful during this case. There were some terms and techniques he didn't quite understand but he fully intended on getting Doctor Reid, Miss Jareau or Miss Garcia to explain them more fully to him.

Looking at his final choices of novels, Ed grimaced a little. He'd never been a fan of non-fiction or fantasy novels and he downright refused to even consider touching romance novels but he was limited in his choices so, grimacing a little, he drew one of the fantasy novels towards himself and started reading. And was abruptly interrupted by the door to the meeting room swinging rather violently open. Startled, he slammed his book shut and was quickly standing and readying himself to draw his automail blade before he recognised the intruder.

"For fuck's sake, Mustang! Don't do that!" Ed exclaimed, moving out of his defensive position he'd automatically taken up. Edward could see James standing behind Mustang, ready to remove him if the blonde should ask. Ed could see that the man was nervous but he was doing a hell of a job not showing it. Mustang, however, looked a strange mixture of angry, really angry and relieved. Ed wasn't as confused by Mustang's reaction, not after what he'd admitted last night, but he knew that he was most likely in for a lecture and when Mustang lectured, it lasted a while. He knew that from experience, lots of experience. So before Mustang could get started, Ed spoke.

"James, it's okay. He's my boss. I can handle him." Edward smiled at the clerk, who looked quite relieved at the fact he needn't step in to help. Nodding, he turned and headed back for the relative safety of his desk. As soon as James turned, Mustang had shut the door and faced Edward.

"Before you start your lecture-" Ed started but Mustang cut him off.

"I'm not going to lecture you, Ed." Mustang shook his head. Ed's eyes widened in surprise.

"You're not?" He asked, a little incredulously. Mustang had never turned down an opportunity to lecture or gloat. Maybe he wasn't feeling well?

"No, I'm not." Mustang said as he moved towards a chair and sat down. Ed took the hint and followed his lead, choosing the chair next to his boss, still looking a little startled at not being lectured. "I know you had a nightmare last night. You woke me up when you woke up." Ed flushed a little. He hated showing any sort of weakness in front of people.

"I'm sorry. I didn't mean to wake you." Ed apologised. Now it was Mustang's turn to be surprised. Ed rarely apologised to anyone whose name wasn't 'Alphonse'. He barely even said sorry to Winry or his teacher. In fact, Mustang could count the number of times Ed had ever apologised to him on one hand. Ed smirked at the shocked look on his superior's face. "Don't look so surprised. I do know how to say sorry." Mustang mentally shook himself out of it.

"Obviously but you don't need to apologise. Well, not for waking me anyway. I'd honestly prefer you to wake me if you ever have another nightmare. I'm not going to pretend to know what your nightmares are like, what with everything you've seen and done, but I do know what it's like to have nightmares that would drive anyone into insomnia. I also know what it means to just have someone there who understands. After the Ishval War, Maes and I both got used to a lot of 1am wake up calls from one another until we found ways to cope with them by ourselves. You don't need to go through this alone. And don't think for a second I'd ever use this against you in the future." Mustang added, pointing a stern finger at Edward. He knew the kid didn't like showing weakness and he also knew that was mainly because he was afraid that Mustang would use it to make fun of him, like he does with his sensitivity about his height. Mustang may be a bastard but he wasn't a total arsehole. There are just some things you never use against people. Edward was almost stunned into silence. He never once thought Mustang would use his nightmares to make fun of him. The man wasn't that much of a prick. But neither had he expected him to actually request that Ed wake him up whenever he had a nightmare. Mustang took his confused silence to also mean he agreed. So he continued with the second part of his little speech. "Also, never take off like that again without telling me. I expected you might've needed to take a walk but I'd expected you to be back relatively quickly, especially since we're in a country completely different to ours. I thought you might've decided to do something idiotic like hunt Harding down yourself." Mustang smirked at the look on Ed's face at his last words.

"Hey! I'm not that stupid!" Ed protested.

"I wouldn't put it past you, what with your track record." Ed huffed in protest but knew he couldn't defend himself there. It wouldn't have been the first time he actively sought out someone who might try to kill him on sight. But still! He scowled in annoyance at his inability to come up with a good defense. Mustang still had that damned smirk on his face. "So are we in agreement? You'll wake me up when you have nightmares and you'll at least tell me where you're going and when you'll be back?" Mustang asked, barely managing to hide the pleading from his voice. He had been so worried when the blonde hadn't come back to the room after an hour. And he knew damn well why and it wasn't solely because of Ed's remarkable ability to attract trouble no matter where he is. He just knew that Maes was laughing at him from beyond the grave. It was the same kind of panic he'd only ever experienced when Elysia once managed to disappear from his sight while he was babysitting her for Gracia. The relief he felt when he found Ed in this room was exactly the same as the relief he felt when he'd finally found Elysia curled up in her mothers closet. He also knew Ed would probably deck him with his automail fist or yell at him or possibly even both if he ever found out just how much Roy cared about him. He knew it was irrational to worry about Ed every time the kid was out of his sight. Edward was unbelievably strong and incredibly smart. More so than Roy himself, not that he'd ever admit that to the blonde. The gloating would never end. But at the same time, he couldn't help but worry about him and his brother. Ed's voice broke him out of his train of thought.

"Fine. But only if you do the same. If you have to go somewhere, you need to tell me too. Equivalent exchange." Ed's eyes and tone of voice left zero room for argument. Not that Roy would've actually protested. It was only fair, after all. Still, Roy was a little surprised that Edward had even asked.

"Deal. Now how about we head back to our room and try to get more sleep?" Roy asked while standing up, noting Ed again copied his movements.

"Okay. I know sleep is more important the older you are." Ed smirked.

"I am not old, shrimp!" Mustang retorted.

"Don't make me punch you in the face, Mustang." Edward threatened but there was no malice in his voice.

"Can you even reach that high?" Mustang couldn't help but laugh at him as he skirted out of Ed's punching range.

"Why don't you come over here and we'll find out, old man?" Ed growled at him, gathering up his borrowed books. Mustang decided to decline that offer, instead opening the door to let Ed through now that the blonde's arms were occupied. Ed accidentally trod on Mustangs foot as he passed him.

"Oops. My bad." He said unconvincingly while Mustang hopped on one foot, cursing. Laughing to himself, Ed made his way back the front counter to give the borrowed books back to James, who seemed pleased to see him still in one piece.

"Thanks for lending me these." Edward smiled as he handed them over. James took them and stowed them away.

"It was no worries. I'm glad you and your boss were able to sort things out." James said as he nodded towards Mustang, who was making his way over to Ed. Edward glanced back at him and smirked.

"Yeah, no need to worry. I can kick his arse any day of the week." Ed laughed as he turned away from James with a half wave and made his way to intercept Mustang. They were just about to head up to their room when they suddenly found themselves facing an irritated Morgan and relieved looking JJ.

"Where were you two?" Morgan demanded but immediately cut both of them off before they could answer that. "Never mind, go back to your room and finish getting dressed. Be back here in no more than five minutes." He ordered the two under dressed alchemists.

"Wait, what? Why? What happened?" Mustang asked as he and Edward were ushered back up to their rooms.

"I got a call from Rossi. Harding killed someone less than ten minutes ago. And he was spotted running from the scene this time."


	8. Chapter 8

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

It took the alchemists precisely two seconds to race straight for their room after the agents relayed the news, much to the amusement of JJ and Morgan. Once in their room, both alchemists were ready in 30 seconds flat. However, Ed grabbed Roy's arm to stop him from leaving. Ignoring Mustang's confused look, Ed grabbed the marker he borrowed the previous day from the hotel staff and uncapped it, turning back to face Mustang.

"Alright, show me some skin." Mustang almost choked while Ed burst out laughing. "Relax, Mustang. I'm going to draw the energy absorbing array I made yesterday on both of us. It needs to be drawn onto the skin directly for it to be effective. So you need to choose a spot you can easily access to activate the array, should we find ourselves in an alchemic fight with Harding." Ed explained, although not all the humour was quite out of his voice. Mustang glared at Ed but started to consider best placement for the array.

"You think Harding will attack us?" He asked as he decided on his abdomen. If he left his shirt loose, he could easily slip a hand up underneath it to activate it. He untucked his shirt and lifted it out of the way so Ed could start drawing the array.

"I don't know. I've just got this... feeling. I can't explain it but something's not adding up for me. I just think we should be prepared for anything." Ed said as he bent slightly so he was eye level with Mustang's gut. Which is something he never thought he'd ever have to do. "Don't flinch. I'm about to start." He added as a warning. Mustang nodded and stood as still as he could, which was hard considering he was slightly ticklish. But it was all over in a matter of seconds, much to Mustang's relief. He wasn't sure if he could take the ticklish feel of the pen much longer. Ed stared at his handiwork for a few extra seconds, double checking the symbols and line work. As with every array, every single part had to be perfect. A rebound would occur if not and Ed wasn't willing to find out just how bad a rebound this particular array would have on the alchemist who activated it. He shuddered just thinking about it. Satisfied, he straightened up and pushed his left jacket sleeves up to expose his flesh forearm. Mustang was thinking about what Ed said, as he finished buttoning his shirt up.

"Oi, make yourself useful, Colonel Bastard." Ed's voice interrupted him. Mustang immediately noticed the kids problem. His sleeves were falling back to cover the area Ed was trying to draw his array on, making it impossible for Ed to finish the array with zero mistakes. He moved to stand on Ed's left and held his sleeves in place. Ed glared, waiting for him to make a comment on his size or jackets but when none were forthcoming, went back to his task.

"What did you mean when you said something wasn't adding up for you?" Mustang queried. He'd had a bad feeling ever since Agent Morgan had told them Harding killed again. Harding knew they were here. He knew who he and Ed were and he knew their reputations weren't exaggerated. So why did he kill someone and risk Ed and Roy catching his trail instead of staying out of sight? He noticed Ed had finished his array and let go of his jacket sleeve. Ed recapped the pen before sighing.

"Come on, we need to get back to the agents. I'll explain on the way." He added the last part to quell any objection Mustang might've had as he moved towards the door. A little pissed at being pushed aside, Mustang followed him out, shutting the door a little more firmly than needed.

"Now, there's some limitations to the array. It probably won't stay active for more than 10 minutes, 15 if we're actually using the alchemic energy. I don't know about you but it takes me nearly 12 hours to recover after a full alchemic fight, one where I nearly drain the energy immediately available to me. And that's back home. Here, we have maybe a quarter of the usual energy available around us. So, it would probably take me nearly four times longer to completely refill my internal supply. With this array, we can absorb the energy at triple the rate we do now. If we activate it during any alchemic fight with Harding, we shouldn't lose much more energy than normal so long as we wrap up the fight before the array deactivates. After that, our transmutations will drain us twice as much as the would back home." Mustang absorbed this information. He wasn't going to take anything Ed told him about alchemy lightly, especially not about an array the kid himself created. But just because the teenager had given him new, vital information, that didn't mean he wasn't going to be diverted from his original question.

"Got it. Now back to my original question. What isn't adding up for you?" Mustang asked, noting they'd almost reached Agents Morgan and Jaraeu, the former looking a little irritated. Edward sighed. He knew that Mustang wouldn't forget but he'd hoped the man would at least let it go for a while. He didn't exactly know 100% what he was thinking but he'd found that bouncing ideas off Al helped him figure out a few things Ed couldn't quite puzzle out on his own. Maybe Mustang could help him in the same way?

"The Truth never told us exactly but I don't think that Harding came here the same way we did. Something else brought him here. If Truth had permitted him to pass than it'd be able to bring him back. Everyone who passes through Truths Gate is linked to it, whether they want to be or not. If Harding got out of hand or started to go against the deal he and Truth made, Truth would simply force him back. Since Truth was forced to cash in the favour I owed it, my guess is that Harding bypassed Truth somehow. I just don't know how. It completely goes against the primary rule of alchemy, equivalent exchange." Once Ed had started, he couldn't stop, even when they had finally reached the two agents. Neither JJ nor Morgan knew what Ed was talking about but they didn't have the time to ask.

"About time you two turned up. Come on, finish whatever the hell you're talking about in the car. We've got to go." Morgan ordered, him and JJ already hurrying towards the entrance. The two alchemists wisely decided not to risk pissing the already irritated agent off even more and followed both of them to the car. Mustang was mulling over what Ed had told him. He could see why something wasn't adding up for Ed. Equivalent exchange was the most important rule when it came to alchemy. It was basically the foundation of alchemic teachings. It was the first thing that every single alchemy student was taught. So how did Harding bypass Truth with a transmutation as massive as dimension travel? It made no sense whatsoever. Mustang was surprised to find himself in the car and already heading towards the latest crime scene. Morgan was driving. He had a feeling Morgan drove whenever he was able, much like Hawkeye. He could only hope that the man wasn't as trigger happy as his lieutenant. He didn't think this man was as likely to fire a warning shot as Hawkeye. He glanced at Ed but the kid was busy looking out the window, seemingly watching the scenery flash by, but he was too used to the blondes habits to be fooled. Ed was trying to figure out an answer that made sense. Ed suddenly sat up, like he'd been electrocuted.

"Mustang-" He started to say but was interrupted by Morgan slamming the brakes on.

"We're here. Let's go find the others." He said shortly, already half out of the car. Whatever Ed was about to say was quickly forgotten as they prepared themselves to follow the agents lead. Neither were strangers to murder scenes but they were in a completely foreign country. They didn't know the laws or procedures here so they had decided to simply follow the agents example. The four of them rejoined everyone else minus Garcia. Ed surmised she was back at the police station working with her computers. Ed faltered a little as he looked up at the other agents. He may not know them well but he was almost certain that something had happened to disturb the agents. They didn't seem like the type to get queasy at a simple murder scene like what they'd been facing with Harding already. Maybe he changed his method to something more gruesome? The scene was already swarming with police, evidence techs and the coroner. Now that he was properly observing the area, he noticed the police officers near them looking oddly at him and Mustang. It was almost like they'd seen a ghost. Ed was starting to get a nasty knot in his gut. There was only one reason he could think that would make those officers and the FBI agents look at them like that. So he adopted the stance he always took with Mustang when he wanted information. Arms crossed, he glared at the agents.

"Which one of our reflections did he kill?" The way he asked left absolutely no room for refusal. Ed almost smirked triumphantly when the agents, excluding Morgan and JJ, masks wavered with expressions of children who'd been caught in a lie. Mustang didn't look surprised. Ed assumed he'd also figured out what the shocked atmosphere meant.

"Ed-" Prentiss began, her voice adopting the tone one would use when telling someone about a close ones death but Ed interrupted her.

"Which one?" His voice was even more demanding this time, his expression showing no room for argument. Silence followed his demand. He was about to ask a third time but Hotch chose that time to answer him.

"You, Edward. You were killed."


	9. Chapter 9

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

_"You, Edward. You were killed."_

Edward didn't know who looked more shocked, him or Mustang. He also couldn't figure out exactly what he was feeling. His reflection in this world had been killed. In a way, Harding had killed him. After all, that was the prick's MO. Go after the reflections of the Amestris alchemists. Ed wasn't surprised Harding had managed to find his reflection here. He was starting to suspect this New York City was Central's reflection. What did surprise him was the timing of his 'death'. There was absolutely no way Harding just  _happened_  across his reflection so soon after Mustang and himself arrived and Harding's awareness of the fact. This had to be Harding's not-so-subtle way of calling himself and Mustang out. But why right now? If Ed was correct, Harding specifically went out looking for his or Mustangs reflection. Obviously, he'd found Ed's reflection first. But the smartest move after attacking them their first night here would have been to lay low. Maybe Harding thought that seeing one of them dead would be enough to rattle them? Edward was so deep in thought that he never heard Mustang or the agents speak. He was broken out of his thoughts by a touch on his flesh shoulder. Jerking his head up, reflex forcing him to start bringing his hands together but recognition forced him to stop. Mustang was looking down on him with something like worry, his hand on Ed's shoulder.

"Huh? What happened?" Ed wasn't completely surprised he spaced out. Al always got up him for doing so, especially in the middle of important things or whenever Mustang was assigning him missions. His brain just tuned everything else out when he was trying to think through a difficult problem. "Was someone talking to me?"

Mustang almost sighed, either with annoyance or relief. He wasn't quite sure which yet. The agents looked a little concerned with Ed's reaction to finding out Harding had targeted him via this worlds version of him. They'd taken his silence as shock instead of his typical self, which wasn't surprising as they barely knew him.

"Was my reflection killed the same as the others?" Edward asked suddenly, startling the agents out of their thoughts. Ed stood there, waiting for their answer expectantly. From the expressions on their faces, neither the agents nor Mustang expected such a question from him. Ed sighed. "Guys, I will go look for myself if none of you answer my question." Ed really didn't want to follow through with that threat. He could handle seeing dead bodies, he hated it but he was rather used to it now. However, the thought of seeing himself dead skeeved him out something fierce. He shuddered inwardly. Nope, he really wanted to avoid that. Thankfully, it looked like the agents wanted to avoid that as well, although they had their own reasons for it. Hotch had decided to answer him.

"No, he wasn't. His body was also staged, which is also a change in MO." Hotch sounded a tad annoyed at that. A killer who varies his MO only does so for a reason and Hotch hated not knowing that reason. Mustang frowned. He was thinking along the same lines as Hotch and found he was unknowingly in agreement with the agent.

"How was he killed and staged?" Edward's question snapped Mustang out of his thoughts. Mustang could sense where Ed was going with his questions. If the murder was different, there must be a reason. And since the only difference between this murder and the last was the fact that himself and Ed were in this dimension, the only reason to kill this victim differently was to send a message to the two alchemists.

"He was shot through the heart and dragged into an old phone booth." Edward felt like he'd just had ice water dumped on him. Mustang looked like he'd seen a ghost or was going to throw up. Maybe both. Edward was 98% certain he looked exactly the same. He felt his shock slowly turn into anger. There were very few things in his life that were off limits to being used like this and, as far as he was concerned, Harding had just given Ed permission to give him a beat down even the Homonculi would be scared of.

"Does that mean something to you?" JJ's soft voice broke through the anger and sorrow that surrounded the alchemists. Ed felt his seething hatred for Harding dull down to seething anger so that he could speak clearly. It wouldn't do to take his anger out on the agents. They didn't understand why this affect the alchemists so much, after all. But once he'd explained this, Edward fully intended to locate and finish this mission once and for all. He was sure Mustang would be on board with him.

"A couple of years ago, a soldier of our military, Maes Hughes, was shot and killed in a phone booth. He was Mustang's best friend and he was my friend too. He actually acted more like a big brother/father towards me and my brother. He was killed because of me. He'd found out vital information he wasn't supposed to and tried to pass it on to Mustang so that we could better prepare ourselves. There weren't many people in the military who weren't aware of the fact that Maes and Mustang were best friends or that Maes treated my brother and I like family. Harding certainly would've known about how his death affected us." The guilt Edward felt was evident in his voice and expression. Before any of the agents could say anything, Mustang spoke.

"Edward, you know his death wasn't your fault. You didn't kill him. No one blames you for it." Mustang still looked like he was going to be sick but he couldn't listen to Ed continue to beat himself up over something he had no control over. Maes's death still affected him to this day but never once did he blame Edward or Alphonse for it and he determined to keep reminding Edward of it until the blonde believed him.

"I may not have killed him but he was killed because of me and you know it." Ed snapped back but his voice lacked his usual bite. Mustang could say what he liked but Edward knew the truth of it. Before Mustang could continue arguing, Edward spoke to the agents. "Which direction was Harding heading when he fled? And how long ago did he leave?"

Mustang sighed. He'd recovered from the shock he felt hearing about how this victim was murdered. He knew this killing would be affecting Edward at least as much as it affected him, if not more thanks to the added surprise of the victim being Ed's reflection. But he also knew when to stop pushing the blonde. This would have to be resolved at another time.

"He was seen running that way, towards some empty buildings around an hour ago now." Prentiss said, pointing to her left. Edward nodded in acknowledgement and started moving in the direction she indicated.

"Hey, where are you going?" Mustang and Morgan both asked at the same time. Edward turned around to stare them all down. Lesser men and women would've flinched at the anger in his eyes.

"I'm going to find Harding and I'm going to make him beg for his death." Edward stated simply. "I'm going to use my searching array to locate him. I have a feeling he'll be hiding nearby to watch our reactions to my reflections death. So I shouldn't be stretching my limits too much. Once I've located the bastard,Mustang and I are going to end this mission." With that, Ed continued his trek towards the buildings Prentiss had indicated. Mustang didn't think twice. He followed suit. He was very quickly joined by the FBI agents, who'd decided that maybe Ed needed back up. Edward stopped just in front of the building that Prentiss had been pointing too.

"Is this where he was seen last?" Edward asked. After Prentiss consulted her notes and confirmed it, Ed headed straight for an alleyway next to the building. Once he was concealed in it's shadows, Ed brought his hands close together and started preparing himself to perform the transmutation.

"Are you sure you can do this? You had trouble seeing in all directions during the test run." Mustang helpfully reminded him. Ed didn't bother opening his eyes when he responded.

"Of course I'm sure, Mustang. I redesigned the array last night so I should be able to make the wave go in every direction instead of just the one. Now, zip it so I can do this." Mustang decided to do just that. Edward was completely still for a few more seconds before clapping and spreading his arms out in front of him. For Mustang and and Prentiss, this was a new experience. Edward's eyes snapped open and shone with the alchemic energy from the internal array he activated. The energy he released made his clothes and braid dance like he was caught in a windstorm but soon stopped as Ed forced the energy outwards in a circle around him. He immediately sensed Mustang and the agents but ignored their energy and made the wave expand further and further. He didn't sense an awful lot of people, mainly a few drunks and homeless people. The biggest group so far were the police officers and crime scene technicians. He continued expanding the wave, stretching it further and further, going way past his test run. He was already beginning to feel the effects of this transmutation. He'd need to activate his energy absorbing array as soon as he stopped this transmutation. Further and further, he had to keep going. He had to find Harding.  _Wait, what was that?_  He saw another colour. Black, this time. He narrowed his focus and concentrated solely on that black and its surroundings. But the colour was moving.  _Damn! He didn't know the area well enough to recognise where it was going_. Quickly he focused on the surroundings of the black energy, trying to discern any unique feature that would be easily recognised. He needed to hurry. He could feel himself running out of alchemic energy. If he kept this up, he'd collapse.  _There!_  Satisfied he'd found a good landmark, he shut his eyes and stopped the transmutation.

The effect was immediate. He dropped like a stone but didn't end up introducing his face to the pavement like he'd expected. Instead, he felt himself be caught by a pair of arms, one around his waist and one lifted his automail arm and draped it around a set of shoulders. A sideways glance confirmed it was Mustang who'd caught him. Dude was quick when he wanted to be, Ed had to give him that. He didn't have to bother with calming his breathing like he did last time. He was way too exhausted to breath hard. The thought of having to lift his arm and push his sleeves back to activate the absorption array made him want to cry but he needed to gain the energy back. If he wasn't as tired as he was, he might've felt embarrassed at having to lean against Mustang but lean against the man he did. Removing his right arm from around Mustangs neck and ignoring the mans protests, he pushed back his sleeves and quickly activated his array. He could feel the transmutation working immediately. He figured that by the end of the transmutations life, he'd feel only a little worse than he did after the test run yesterday. Mustang had placed his automail arm back around his neck and was still supporting him. The agents were all standing around, unsure of what they could even do. Mustang seemed to be able to support Ed and they all knew that Ed would soon tell them anything he'd learnt so they were content to wait for the blonde to recover.

"How are you feeling, Fullmetal?" Ed was too tired to care about the concern hidden in Mustang's voice.

"Take a wild guess, Mustang." He snapped. Mustang seemed happy with that response for some reason.

"Right, dumb question. Did you locate Harding at least?" Mustang was glad the blonde was okay, even if Ed looked like he could collapse at any second.

"Yeah, I did. Well, sort of. He was on the move when I located him. You should send people out that way," Ed pointed out of the alley and to the right, "about three or four blocks. He was watching us like I thought. Keep an eye out for a shop that has a statue of a person holding a bowl of something on the corner of that block. He was heading straight from that direction when I deactivated the array. Find where he's holing up, if possible. It'd be better to attack him at night. Mustang and I are very good at sneaking around places at night. Plus, you guys definitely can't take him down without us and I'm way too fucking tired to even think about fighting and two alchemists against one is always better." Morgan looked rather insulted that Edward thought they couldn't handle one alchemist without them.

"What makes you think we can't take him down without you? I know he's an alchemist and a killer but he'd be hard pressed dodging bullets, right?" Morgan asked.

"Ordinarily, I'd agree with you. Bullets are very effective against alchemists. However, something had been nagging at me this whole time and I think I figured out the answer to the problem. Truth never mentioned letting Harding pass, which means he didn't pass through the Gate with Truth's permission. He had to have hijacked the Gate using alchemy. And there isn't an alchemist, alive or dead, who is knowledgeable or powerful enough to do that without Truth finding out. Not even me. Which means Harding bypassed the laws of Alchemy somehow." He heard Mustang's shocked gasp and knew the man had figured it out for himself but he continued on. "Harding is in possession of a Philosopher's Stone."


	10. Chapter 10

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

As Edward had expected, none of the agents had a clue what he was talking about. He did, however, feel Mustang suddenly do a pretty good imitation of a statue while still supporting most of Ed's weight. Which he was growing ever more grateful for because  _fuck_ , he was beyond exhausted. Like, so tired he was more useless than Mustang in the rain when it came to a fight. He was forced to divert his focus from his exhaustion when Mustang remembered he still needed to breath in order to stay alive.

"Are you serious? Are you certain?" Mustang's whispered voice was beyond tense. Ed could understand why Mustang sounded how he did. He figured it was like telling any of the agents that Harding had an atomic bomb at his disposal (thank Truth for someone leaving that textbook behind). Edward couldn't be 100% certain Harding had a Philosopher's Stone. He didn't sense anything odd about his energy while his array was activated. Having said that, he wasn't looking for a Stone and he had no way of knowing if a Stone takes on the same alchemic energy as its wielder. Sighing, he answered Mustang.

"I am. It's the only thing that makes sense. I can only think of two ways for Harding to dimension hop. Truth or the Stone. Since Truth didn't mention him, I can only assume that he came into possession of a Stone. A fake one but a Stone nonetheless. There  _is_  the possibility that Harding did go through the Gate and Truth is being a dick by not telling us but we should assume the worse. I can't be completely certain either way, not without seeing the Stone for myself so I'm going with worst case scenario." Edward explained, a little apologetically. He had his fill of Stone's and those who wielded them. Although, if he were being truthful, Lust turned out not so bad. She was the only Homonculi whose death Ed almost regretted. Mustang probably had a response but the agents decided to come out of their stupor now.

"I'm assuming this Stone is bad?" Hotch asked, sounding rather defeated. He'd realised that good news rarely occurred around these two. Ed and Roy exchanged a look. Bad? That was the understatement of the freaking century. Mustang looked at Ed but once he realised the blonde wasn't about to answer, he took over.

"Yes. The Stone is bad. The fact that Harding might be in possession of one complicates things extensively. Him having that Stone puts Ed and I at a huge disadvantage. We'll be happy to explain it to you in more detail but not here. It's way too sensitive a topic. Also, if we keep standing around here, Ed's gonna fall unconscious." Ed would've argued but Mustang wasn't wrong. His absorbing array had run its course and while he felt a lot better than he did 10 minutes ago, he still felt worse than yesterday. He was certain that if Mustang wasn't acting as a crutch, Ed would've curled up in the dirty alley and given exactly zero fucks. The fact that Ed didn't argue kind of drove Mustang's point home for both the agents and Mustang himself. If Ed didn't argue, he was worse off than they thought.

"Alright, we'll head back to the station. We need to organise some officers to do a canvas anyway and Edward is welcome to camp on the couch in the office until we get Harding's exact location and he's recovered." Hotch decided. Upon hearing no immediate arguments, Hotch lead the way back to the cars. Mustang tightened his grip on Ed and helped the blonde alchemist. He noted that Rossi and Prentiss had automatically fallen behind them, to protect their backs should Harding be opportunistic enough to attack them. The chances were slim considering Ed had located and tracked the man four blocks away but Mustang still appreciated the thought. It's what he would've expected from his team back home. Ed simply appreciated the fact that he'd soon be able to lie down and recuperate.  _And Al said I never got enough sleep._ He chuckled to himself. He honestly didn't remember the trip to the car nor the subsequent drive to the station. He didn't notice that Mustang kept his arm around him the whole car trip. He did notice Mustang and Miss Jaraeu both helped him to the office and onto the couch. He immediately laid himself down and curled up under the blanket that someone draped over him. Mustang knelt next to him as he fought to stay awake a little longer to hear what Mustang was obviously about to say.

"Get some sleep, shrimp. We'll need your genius to beat Harding and the Stone soon." Mustang's usual smug face seemed forced, the worry was too evident in his eyes.

"I always knew you were a softie." Edward smirked weakly. Mustang's responding chuckle was the last thing Ed heard before he gave into exhaustion.

* * *

 

The whole room was quiet, the only exception was Ed's breathing. Mustang knew the agents were being very patient and were waiting for Mustang to initiate the conversation. However, Mustang wanted to wait a few more minutes, he wanted to be sure that Ed was definitely asleep before he began. Ed's breathing finally evened out and Roy had never felt more relieved. Wiping a hand over his face, he straightened and sat next to Ed on the couch.

"Okay, what do you want to know?" He finally broke the silence, looking up at the agents. The agents were apparently collecting their thoughts because no one spoke for a few moments. Hotch, as usual, was the first to speak.

"I think we'd all like to know what a Philosopher's Stone is, to start with." Mustang nodded. It really was the only logical question to start with. He leaned slightly into the back of the couch, elbow on arm rest, chin on hand.

"Okay. This might take a little bit of explaining, so please bare with me." He barely noticed the nods as he continued. "The Philosopher's Stone is a blood red stone created from alchemy. It enables its wielder to be able to bypass the laws of alchemy that Ed told you about when we first sat in this office. Basically, the only limits on what you can with the Stone is your imagination and the life of the Stone itself. The real Stone can last centuries. A fake Stone, which is what we expect Harding to have, will only last for a set amount of transmutations. The reason Ed and I are at a disadvantage here is because we are still bound by the laws of alchemy. Harding is not." Mustang stopped there. There were certain things he'd only answer if asked. Otherwise, he was keeping them to himself and Ed. The agents absorbed and chewed over the information they were given and seemed to realise the implications that meant.

"So if we were to go up against him?" Morgan slowly asked, fairly certain he knew what the answer would be.

"He would more than likely destroy you with one move." Mustang confirmed. "My first lieutenant is an expert marksmen and an undefeated sniper and even she couldn't get a shot in, the rare times that we went up against a Stone instead of Ed and his brother." The agents reactions were more or less what Mustang expected.

"So why don't you and Ed create Stones before you face off with Harding? Even the playing field?" Prentiss asked. Mustang sighed. He should've known Ed's bad luck would transfer to him while the kid was dead to the world.

"Because Ed and I would have to sacrifice thousands of people in order to make one Stone." Hotch had to give him credit; Mustang didn't sugarcoat anything. But still...

"Thousands of people?!" JJ was horrified and she voiced exactly what the others were thinking.

"Yes. The Stone uses human souls to bypass the laws of alchemy. Nothing is worth a human soul. That's why bringing the dead back is taboo. However, if you were to exchange a human soul in order to create something, it would be within the rules of equivalent exchange. As long as you give equal or more of what you want to exchange, the rule applies. It's only when you exchange something worth less than what you want to achieve that arrays will rebound on their casters. With the Stone, you're always exchanging more than what you want in return so you can do anything." Mustang explained as thoroughly as he could. This was definitely more Ed's forte but he hoped he'd explained it simply enough. He didn't really know how to dumb it down anymore. He waited quietly, just listening to Ed breathing, waiting for any questions the agents might still have. He was glad the blonde was getting some rest at last. He knew that the first night they were here was the first night in a long time that the blonde had gotten proper rest and that was purely because he was so tired. But any rest he'd gained was lost after the test run and nightmare last night, not to mention everything that happened today. Hell, today had taken a toll on Mustang. He was going to kill Harding for doing what he did. Killing people with alchemy just because they resembled Amestrian Alchemists was horrible enough but the fact that he decided to call him and Ed out in the way he did, that had crossed the line. Harding had made this personal and, Stone or not, Mustang was gonna make him regret it and he knew Ed felt the exact same way. He was soon distracted from his thoughts by Morgan using one of those cell phones. It never failed to fascinate him, how this world didn't need landlines to contact people. He wondered if they could take this technology back to Amestris. Maybe he'd ask the young agent, Reid if he recalled, to give him a run down on how it all worked. He seemed really intelligent, like Ed. Mustang frowned. If he was like Ed though, maybe he should let him explain it all to Ed. Edward would probably be able to understand all the technical jargon Reid would likely spout off. Movement brought him back from his thoughts.

"What's going on?" He asked, a quick glance confirmed the noise hadn't even disturbed Ed.  _Wow that kid can sleep when he wants too_.

"Garcia is using traffic cams and other surveillance in the area Ed told us Harding was in to track him. Rossi, Morgan, Prentiss and Reid are going to join a group of officers and canvas the area as well, just in case someone saw Harding and there weren't any cameras in the area. JJ and I will be staying here to coordinate the police here and any tips that come in. Also, JJ is our point person when it comes to dealing with the press so if any tips come in that we feel the public should be made aware of, she works with the press to get the information out. We were just going to brief the locals. We'll be back shortly." Hotch explained, even as everyone was practically out the door.

"Before you leave," Mustang grabbed the attention of the agents, "make sure to ask them to report any sightings of bright blue, red or purple flashes of light and tell them to stay away from the area. And if they see any circles drawn anywhere, make sure they know not to touch them. Tell them they're marks for traps or something, just make sure they stay away from them." Mustang warned.

"No problems. We'll add that to our briefing. JJ and I will be back in a couple of hours. Get some rest, Colonel. You may be asked to help with any tips or reports we get in." With that, Hotch and the others left the room, the door clicking softly shut behind them. For a few minutes, Mustang sat quietly but he got bored very quickly. He got up and grabbed the case files before returning to his spot next to Ed. He'd decided to use this time to go over the files properly so that he was aware of every fact. For the next hour, the only sound in the room were pages being turned and Ed's even breaths. Mustang soon found out that it didn't matter what dimension you were in, paperwork was still boring. However, setting the paperwork on fire here might be a bad move. After all, Mustang knew that Hotch at the very least didn't trust him. While setting the files on fire might be a way to alleviate the boredom for a moment, Mustang knew it could be seen as something more aggressive. So while he decided against the urge to snap his fingers, he still wanted something to happen. But it was another hour or so until his wish was granted. A noise to his right drew his attention away from the paperwork he was pretending to read. Ed's eyes were flickering open.

"You okay, kid?" Mustang asked as he watched Ed sit himself up, rubbing his eyes with his flesh hand. Edward blinked a few more times before he focused on Mustang.

"Hmm? Yeah, totally fine. How long was I out?" Edward did not sound fine. His voice was rough from sleep and he still looked like he needed another good 12 hours before he was fully rested.

"Well, you were out for a grand total of four hours. Why don't you get more sleep? Nothing's happened and, trust me when I say this, you look worse than Father did when we beat him." Mustang informed him.

"Thanks for that." Ed snorted. "But I'm not tired anymore."

"Really?" Mustang raised his eyebrow in disbelief.

"Okay, I am but I can't get back to sleep. But that's not a problem. As long as I don't do anything, I'll still get my alchemic energy levels back up." Edward said assuredly.

"And what about your actual health, Ed? Using that much alchemic energy isn't good for it. That and your sleeping habits. You need more sleep." Mustang told him. Edward rolled his eyes.

"I know that but I can't help it. I'm tired but my brain won't let me sleep. It'll sort itself out in time. Besides, like I said, if I just rest for a few more hours, I'll be right to go. Stop worrying." Ed waved his concerns off, sitting himself up more so that his back was resting in between the arm rest and the back of the couch. Mustang sighed. He knew that Edward was stubborn. He spent the last four or so years learning just how stubborn the kid was. He knew no amount of arguing or pestering would serve his purpose.

"Fine. But you're not allowed to do so much as make your own coffee. You stay on this couch, got it?" Mustang told him which Ed answered his a huffed 'fine' and roll of the eyes.

"Where are the agents anyway?" Ed asked after a total of 30 seconds of quiet.

"They're briefing the local police officers, canvassing and dealing with public tips and the media. Agents Hotch and Jareau will apparently be back soon." Mustang informed him before going back to the riveting paperwork.

"Oh." Was all Ed said for a few seconds. And then, "What you reading?"

"The files on this case. In case there's something we missed that might end up being an important detail later on." Mustang had to reread that paragraph he was on. Ed fidgeted for a bit before;

"Can I read whatever you have?" Upon noticing Mustangs look of annoyance, Ed continued. "What? I'm bored! And there's nothing to do! Besides, you might miss something too." Mustang didn't even acknowledge that with a response. He merely handed Ed the two files he'd already read. Ed grabbed them with a quick thanks and quickly opened the first one up to read. Soon, all they could hear was each others breathing and the rhythmic flip of pages.


	11. Chapter 11

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

JJ and Hotch walked back into the makeshift HQ to find the two alchemists talking on the couch, surrounded by their case files on Harding. They hadn't noticed them enter the room as yet so both agents took the time to study the alchemists when they didn't know they had an audience. They couldn't hear what they were talking about but whatever it was was obviously a very interesting topic. They both had a sparkle in their eyes, like they were enjoying it but their body language read like they were arguing over something. They also looked completely relaxed, not like how they were around the agents and even less so around anyone else. That little fact confirmed that they still didn't trust them completely, which both JJ and Hotch understood. Even though the agents had all warmed up to the alchemists and even got along with them, especially JJ, Reid and Ed, they knew that the alchemists wouldn't trust them completely in the space of a few days. Hell, Roy had mentioned it'd taken nearly five years for him and Ed to have a pleasant conversation. While they'd never asked and the two hadn't said anything, all the members of the BAU knew that Ed and Roy hadn't had it easy. Plus, they figured that trust wasn't easy for members of their military to come by. So they didn't take it personally because most of the agents didn't trust the alchemists completely either. JJ decided to interrupt the arguing alchemists before she and Hotch got caught spying.

"Hey, good to see you up, Edward. How are you feeling?" She asked, walking over to the chair closest to the couch, barely managing to hide a smirk at making both men jump at the interruption.

"Hey, Miss Jareau. I'm good, I just need to rest until we get an exact location on Harding." He smiled at her, an action that was soon reciprocated by JJ.

"That's great! You had me a little worried there. Do you want some breakfast? Or coffee, at least?" She had been worried about the blonde and now her mothering side was starting to come out. She knew the others joked about her being the teams mum but she didn't mind it.

"Actually, that'd be great. I'm starving." Ed scratched the back of his head, grinning a little sheepishly.

"Big surprise." Mustang muttered loud enough to be heard by the blondes.

"Oh, shut it, you!" Ed snapped, immediately on the defensive. JJ wisely decided to shift Ed's focus back to food before an argument could break out.

"What would you like, Ed?" Ed's attention immediately returned to JJ as he thought about it.

"Do you guys have pancakes here?" He asked hopefully. JJ's nod made him very happy. "Can I have some pancakes and coffee, please?" He could feel Mustang's bemused look aimed at him but he refused to pay it any attention. He was about to get pancakes that weren't made by a stressed Winry or an armoured Al! He loved those two to bits but being overtired or having no sense of smell made them very bad pancake cooks.

"Pancakes it is. Do you two want anything different?" JJ smiled at Ed before turning her attention to the two men near her. With no new requests, she left to make some phone calls about places that delivered pancakes. With his focus off of food for now, Ed turned his eyes to Hotch.

"Did you guys find anything new while I was out?" He asked, leaning back into the couch. Mustang was also waiting for Hotch's reply.

"We've had a few tips come in that sounded promising and were in the area you indicated, Ed, so we've been following up with those. Garcia is checking every camera she can access for footage of him. Morgan, Rossi and Reid struck out with their search. Prentiss was following up on something so I'm waiting for her report. The canvas was successful. We paid a few homeless people and they gave us some more good leads, for the most part. We're closing in. I can feel it. You should rest up while you can, both of you. I have a feeling we'll need you very shortly." Mustang and Ed both nodded. This sort of briefing was what they were used too. Roy more than Ed since Ed generally got his briefings from Mustang and they usually ended up yelling at each other until Al intervened or Hawkeye fired her gun, whichever came first. So Ed made himself more comfy, continuing his mission to read all the case files while Mustang and Hotch exchanged more words, content to wait for his pancakes.

An hour later saw a very happy, well-fed and well-rested Edward. Morgan, Rossi and Reid had joined JJ, Hotch and the alchemists by this stage. JJ had had the foresight to order enough pancakes to feed twenty people. After Ed was done with them, there were just enough to feed everyone else, a fact that amused everyone. Prentiss had reported in to say that she was on her way in. She'd located where a homeless woman had told her Harding was supposed to be holed up. She and three regular police officers had staked the place out, hoping to catch a glimpse of the man so they had solid evidence he was there before anyone could make a plan to do anything. Once they confirmed he was there, she and the others had made their way back to the station so the BAU and alchemists could come up with a joint plan to capture Harding. She rejoined the rest of her team 20 minutes later. Reid was the first one to notice her, sending her a greeting from where he was sitting next to Ed, who was currently reading a rather thick book. After being told by Hotch that she needed to eat first, Prentiss was informed by Rossi that Reid had heard about Ed sneaking out of his room in the middle of the night and borrowing books from the hotels lost and found so he brought in a couple he'd brought with him to loan the blonde. Ed had loudly proclaimed that it was the nicest thing anyone in the room had done for him, minus those who'd gotten him food. Prentiss had chuckled as she finished the last of her pancake. Getting the go ahead from Hotch, she stood, commanding everyone's attention.

"Three officers and I located Harding about five blocks from the crime scene. We found him three blocks away from where Ed saw him heading. After a quick recon, I can confirm he's inside an older building, one that looks to be shut down or used by squatters. While we saw no evidence of anyone else there, it is a large building so we can't be certain. We also don't know if he's still armed but we should consider him such. There was something on the ground in front of the entrance to the building but we couldn't make it out without being spotted. We couldn't see any flashes of lights or anything like that. Harding was just pacing around the room. He looks like he's gearing up for a fight." Prentiss finished her report.

"Did he do anything else? Other than the pacing?" Mustang asked after a moment.

"Yeah, he kept glancing at his left hand. It looked like he was reassuring himself that something was there." Prentiss replied.

"Makes sense. If we're right about the Stone, he'd be paranoid about losing it just before he goes up against us. So we can assume it's in his left hand." Ed surmised. Turning to Mustang he asked, "How did he normally activate arrays back in Amestris?" Mustang looked at him for a moment before answering.

"I'm pretty sure he has a cuff that has his array carved onto it. I think he wears it on his right wrist though." Mustang said after a few moments of contemplation. Ed raised a brow at him.

"You don't sound very sure, Mustang."

"What do you expect? I've never had the displeasure of meeting the man, let alone learning his alchemic quirks." Mustang snarked at him. Edward just rolled his eyes.

"Whatever, old man. So the theory we're going with is that he has a Stone in his left hand and he has a cuff with an alchemic array etched into it on his right. He also has a gun and there's possibly an array armed in front of the entrance. Did I miss anything?" Ed asked after the brief summary. Head shakes were the only answers forthcoming. "Okay, so how do you lot want to go about doing this?" Ed asked, looking directly at Hotch.

"Since when have you asked before acting?" Mustang's jaw was nearly on the floor. Another brow raise from Ed was the answer he got first.

"Mustang, even I'm not irresponsible enough to go after a wanted fugitive by myself in a country I have zero understanding of. I'd prefer them to come up with a plan of attack since they have the experience of working in this country and its laws." Ed stated rationally. Mustang couldn't believe it. Even the agents seemed mildly shocked. Ed just rolled his eyes, waiting for someone to answer him. After a moment, Hotch got over his shock and answered the teenager.

"Well, given what Prentiss just told us, you two are going to be exceptionally vital to our plans. I'd like for you two to stake out Harding's hideout and disable whatever traps you can. We'll get the blueprints of the building from Garcia and decide our positions based on it to cover the two of you. I'll be positioned on a rooftop with a good sniper point, if possible. While I wish that Harding would simply surrender, I doubt it'll be that easy so you two will need to draw him out into a trap. We can finalise that when we get a map of the area in here. Now, I know that an alchemy fight won't be predictable but I'm hoping that if you get him in a position where we can surround him, he'll give up. However, if he doesn't, I'll be leaving his capture to you two. All I ask is that you don't get yourselves or us killed and that you try not to kill him." Hotch added that last part as an afterthought. He fully expected Harding to make everything very difficult so he had decided to make sure the alchemists knew they had free rein if the first plan didn't work.

"Okay. That's a plan I can work with. You?" Edward asked Mustang, who simply nodded. "Let's get those documents you need so we can get going." Hotch nodded his agreement and asked Morgan to call Garcia and Reid to find them a map. 15 minutes later, they had both laid out on the table in front of everyone. Morgan had taken point this time.

"Okay so this is the blueprint for the building Prentiss saw Harding in. It's a one story building that was once a clothing store. This means we have a few areas that he might be hiding in. There's the changing room area, with four changing rooms in it. There's the main shop floor, the office, the storeroom and the staff toilet and break rooms. That means he could be in any one of these nine places. It's also possible he may have booby-trapped these places which means that if our plan to lure him out doesn't work, only Mustang and Edward can go in. If it comes to that, your job" he looked at the alchemists at this point, "is to defuse any traps you can and secure Harding, if possible. The arrest has to be made by one of us since neither of you are law enforcement or citizens here. Got it?" He moved on after the two nodded their agreement. "Now, here's the map of the area. The building is here. It's got a building on either side but you can't access either building from in there. There's an alleyway running behind it that's blocked off at one end. There is a door that leads out to it so I want JJ and Rossi watching that door. There's all these buildings across the street but like this one, their either abandoned or used as storage or are warehouses so there shouldn't be many civilians around. He can get out onto the street by the front doors or the two display windows, if he really wanted to. I'd like Prentiss on the right of the building to cover that window and door and Reid on the other side to cover that window and door. I will be here, at the mouth of the alley to provide back up should he slip through anyone. Hotch will be across this street positioned here."He jabbed a finger at a two story warehouse directly across from the building. "He will provide sniper assistance for Prentiss and Reid. He'll also have vantage points of the buildings next door, should Harding have realised we found him and moved to one to try and ambush us. Any questions so far?" He paused, looking around the room but receiving no questions. "Okay, good. Edward and Mustang, where do you think you should enter the building?" He looked at both alchemists, who seemed to be having a silent conversation. Ed spoke first.

"Mustang, can you use your flames to blow a hole through a wall?" Ed asked. He received an affronted look in return.

"Of course I can." Mustang huffed.

"Good. Because I think you should go through this building," Ed indicated to the one to the left, "and blow a hole in the wall that separates this building from that one. I'll do the same but from the other side. That way, we can make sure Harding isn't hiding in the adjoining buildings and it'll be a really good way to make sure he can't use the Stone to create an opening himself to escape through." Ed sounded very pleased with his plan.

"You just want to blow something up." Mustang accused, sounding very amused at the blonde.

"Do not!" Ed immediately said but added a mumbled 'shut up' to Mustangs raised brow. Mustang chuckled at him before turning his attention to the agents.

"It's a good idea. Any traps on the other sides of those walls could be triggered by the falling debris so that'll save us some extra work. And Harding would probably not expect me to let Fullmetal destroy anything over here so it'll be an added surprise, giving us a good window to secure him before he can react." Mustang drew on his military experience to realise the good points to Ed's plan. "Plus, we can fix the walls after we've gotten Harding." He added as a way to appease any arguments about property damage before they came up. Morgan nodded. He could see the value of this plan.

"Any objections?" Morgan asked the group but none arose. "Is there anything else anyone wants to ask or say about the plan before we head out?"

"Yes. Mustang and I will be activating our absorbing arrays just before our grand entrance. That will give us 15 minutes of being able to fight at our normal level. However, if you get the opportunity to shoot him, take it. He has one up on us with that Stone with no guarantee we can win, especially since we have to rely on our array to keep up our energy intake and he won't lose any energy using the Stone. The sooner he goes down, the less chance there is of one of us being killed." Edward stated.

"Fullmetal's right. If you've got the shot, take it. Don't worry about us. We'll focus on getting that Stone away from him, if we can. He'll be a lot easier to beat without it, which means it'll be safer for you guys to arrest him." Mustang added.

"Okay, so everyone is clear on the plan. JJ and Rossi will cover the back. Prentiss will cover the front right, Reid the front left. Hotch will spot from the opposite building. I'll cover the alleyway's mouth. Ed will enter through the building closest to Reid, Mustang from the building closest to Prentiss. Hopefully Harding will be surprised enough for Ed and Mustang to capture him and we'll arrest him. If not, Ed and Mustang will try to subdue him or create an opening for someone to get a shot at him. Our aim is to capture him alive unless he proves to be too dangerous to do so. Got it?" Nods all around. "Good. Let's gear up and head out." Morgan ordered. Everyone except the alchemists moved to do so. Morgan noticed. "I said gear up."

"We heard. We are." Mustang informed.

"So you've got your earpieces in? Your mics are on?" Morgan asked doubtfully. Ed wasn't the only one who looked confused.

"And those would be?" Came the slightly sarcastic reply courtesy of the blonde alchemist.

"So that would be a 'no'?" Morgan sighed before grabbing his set. Holding up his earpiece, he explained. "This is a device you put in your ear. It conveys messages from whichever team member happens to be talking into their mic at the time." He held up the mic to show them. "This device lets you talk to the anyone on the same frequency and in range of the device. You press it like this, talk into it and release so that others can talk back through the earpiece." Morgan finished his explanation. Ed looked fascinated by them, Mustang looked mildly impressed. Morgan grabbed two sets of each and passed them to the alchemists. "Here, Reid will help you with them. Once you understand how to use them and they're set up, we'll head out." Reid had turned at the sound of his name and moved over to the alchemists to begin helping them. It took nearly 20 minutes because Edward had a lot of questions but eventually they were set up and knew how to use them.

"Everyone set?" Hotch asked and got seven affirmative replies. "Let's head out."


	12. Chapter 12

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

The car ride was thick with tension. Neither the agents nor the alchemists were strangers to this sort of tension though. It was the tension created from everyone who nearby doing the exact same thing; running through the worst case scenarios. As usual, they were separated into two cars with the only difference being that the alchemists were riding in the second car. Hotch had been of the opinion that Harding might foresee them coming and chose to ambush them, knowing the alchemists usually traveled in the front car. So, Hotch had suggested they travel in the second car, just in case. The alchemists had simply agreed. It was quiet in both cars when a sudden ringing noise startled everyone out of their pre-mission thoughts. Rossi pressed something and a familiar voice called out a greeting.

"Hey everyone, I've got both cars patched in. I'm watching the live feed from the cameras surrounding Harding and the buildings next to and across from it. So far, he hasn't done anything exciting. No movement, no flashing lights, not a peep. I've got a couple of the cops here watching the feed from when Prentiss left up to when I started, just in case he managed to sneak out then but so far, I've got a whole lot of nada." Garcia sounded slightly annoyed at that.

"Thanks for the update, Garcia. You do have a camera that's got the alleyway opening in its sight, right?" Rossi asked. He knew already that she would have but it didn't hurt to double check.

"You wound me, Rossi. Of course I do. A storage place across the street from it has one aimed right at it." Garcia scoffed in a joking manner.

"Thanks, mama. You're the best." Morgans voice sounded over the phone.

"Of course I am. I'll call you back if Harding moves. Stay safe."

"Always do." A series of beeps indicated the end of the call as soon as Morgan spoke. Ed and Mustang both silently wondered how much easier it'd be if Amestris had access to the same technology. Ed wondered how hard it'd be to get all the information on how to make some of the technology available here before they left. The car slowed down as they turned a corner and both alchemists readied themselves for a fight as the cars slowly drew to a stop, nearly a block away from their target. The group gathered just in front of the first car, all facing towards where they knew Harding was supposedly located.

"That's the target building, the grey one with the red door." Hotch indicated as he spoke. "Now, the alley is blocked at both ends by security fences and locked gates. I had Garcia contact as many of the buildings owners as she could and everyone has said their buildings are locked and that the gates and fences were still intact as of yesterday. The only opening we know of is the alley closest to us. I know Garcia said that she hadn't seen anything suspicious yet but is there anyway Harding could've left the building and avoided cameras?" He directed the question to the alchemists. Mustang took the first initiative and answered.

"There's the possibility that he made a tunnel that helped him escape underground but he would have no clue how many cameras we'd have access too. Fullmetal?" He handed the proverbial mic over to his subordinate, who was deep in thought.

"Garcia said she saw no flashes of lights, right?" Without waiting for a response, he continued with his train of thought. "I suppose he could've used our idea and just blown some holes through the adjoining walls until he got out but she would've captured the lights on film. Those windows would've done fuck all to block the light. Do her cameras cover the rooftops as well?" He asked, this time wanting a response. When none were forthcoming, he knew his answer. "Can one of you find out?" JJ nodded and stepped aside to make the call.

"What are you thinking?" Morgan asked, brows furrowed a bit.

"Well, assuming we don't have any camera coverage, he could've used the rooftops to move about unnoticed." Ed explained just as JJ finished up her phone call.

"She says that none of the cameras cover the rooftops." Edward swore softly.

"Okay. We can't do anything unless we know for certain he's in there, right?" Hotch answered his question with a nod. "Okey dokey. I'll get us that confirmation." Mentally preparing his array, he clapped his hands together and activated it. He forced the energy to go outwards in every direction. As he suspected, the buildings were empty, including Harding's hideout. Suddenly, a colour flared in response to his energy. Spinning, he ended up facing the other direction.  _There! Harding was right there!_ He was about to kneel on the ground when Ed realised what he was about to do.

"Mustang! Four down, on my right!" Edward yelled as he ended his transmutation. Pushing his left sleeves up, he activated his second array just as he heard two quick snaps and felt heat rush past him. He looked up just as Harding took cover, the fireballs hitting where he'd been standing just a second before. "He has a Stone. It's a fake, like Father Cornello's but it's still powerful. I could sense its energy this time." He informed Mustang as he readied his automail blade and drew level with the older alchemist.

"Shit. At least we've got confirmation now." Edward scoffed at him.

"Yay for us. Now the plan's all screwed to hell. Now we've gotta figure out a way to get the Stone from him while he's in the open and got the tactical advantage."

"You were actually going to follow the plan? I thought you would've just fallen back on your go-to. You know, blow shit up and hope the bad guy gets caught under it?" Mustang smirked as he poised his hand, ready to snap at the slightest movement.

"Oh, ha ha. You're hilarious. Although now that you mention it..." He said in a thoughtful voice as he moved into a lax version of his fighting stance.

"You are not blowing up any buildings here." Mustang informed him. Ed pouted as Hotch signaled for the agents to spread out, trusting them to make the right call. All of the agents had one eye trained on Harding's last position and the other trained on the alchemists. It was a silent pass over but everyone knew that Ed and Mustang were calling the shots now. After ten seconds of tense silence, Ed's infamous lack of patience got the better of him.

"Come on, Harding. This is boring. We just want to take you back home, although we may have a small side trip first. Apparently, you pissed something off when you skipped dimensions and they'd like a little chat. What do you say? We all know you can't beat Mustang and you sure as shit can't beat me." As much as he would've liked to do otherwise, Mustang stayed quiet. He knew Ed was just trying to goad Harding into revealing his position. Ed had his head cocked to one side as he strained his hearing to try and hear if Harding moved. He was about to try again when something moved in his peripheral vision. Letting his instincts take over, he tackled Mustang to the side moments before a boulder the same size as him smashed into the space just in front of them. As he scrambled up, he glanced at the rooftops just in time to see Harding lean over to see if his attack worked. A quick clap, he slammed his hands onto the boulder and created sharp projectiles that he aimed straight for Harding. A series of snaps and fireballs quickly followed, informing him that Mustang had recovered and rejoined the fight. Ed groaned in frustration as Harding dodged or blocked everything and took off running along the rooftops.

Ed followed no more than a second behind him. Trusting Mustang and the others to follow him, he turned his attention to the fleeing alchemist. He could see a cut on his arm, which gave him a small feeling of pride that quickly vanished when he saw the red light flash across Harding's wound and heal it. Growling as he ran, he utilised every ounce of his training and experience to dodge Harding's continuous attacks. From what Ed gathered, Harding had prepared earlier and gathered numerous small objects that he then used the Stone to turn into larger weapons to throw at him and Mustang. Ed noticed that Harding was only aiming for him and Mustang, ignoring the agents completely. Edward realised Harding had decided to take on the two biggest threats first and he really hoped that decision would come back and bite Harding in the arse. Ed and Mustang continued their own assaults, Mustang snapping and Edward barely slowing down to touch the ground and send up more projectiles, sometimes spikes or stone hands but Harding just kept dodging or destroying. Edward was secretly glad he kept using the Stone. He knew the fakes had a short lifespan and if Harding could wear it out, the Stone would rebound on its user and rebounds were never in the unlucky alchemists favour. That's when Ed noticed a new problem that might work in their favour. Harding was running out of rooftops.

Harding seemed to have noticed it as well and had apparently decided to stop running and simply fight them from the rooftop he was currently standing on. For the next couple of minutes, it was simply an exchange of attacks and dodges when Harding suddenly changed his attack pattern and sent a large attack straight at the agents. Ed reacted quickly, creating cover for them just in time to stop the attack before it landed. Unfortunately, that left him wide open and the next thing he knew, a stone pillar created from the side of the building slammed into him, sending him flying before he crashed into a building behind him. He heard people yelling at him as he fought to get air back into his lungs. Coughing, he rolled onto his hands and knees, trying to assess the injuries he sustained. Thankfully, he didn't appear to have many, his automail arm must've taken the brunt of the damage. Still, he didn't get out quite unscathed. He could feel blood running down his face, at least two of his ribs were broken or badly bruised, his shoulder port hurt like a bitch but Truth kept its word because the automail itself wasn't damaged, his right leg had a decent sized gash on it plus various scrapes and bruises. He had a feeling he'd be a lot of pretty colours tomorrow. Standing up, he gingerly put weight on his leg and was happy to find it could take his weight. Next thing he did was take stock of his surroundings, particularly the fight. The agents were using the cover to line Harding up in their sight, ready to fire when he enters it. Mustang was still sending his flames but they seemed to be getting slower for some reason. Then it clicked.

"Mustang! Activate your array, you idiot!" He yelled at him as he ran forward to take his position up again. "I'll give you some cover so hurry up." Ed clapped his hands together and slammed them into the ground but this time, he was taking no prisoners. He didn't like it when people refused to fight fair, so now he wouldn't. Instead of creating one stone pillar to knock Harding to the ground, he created four. One to hit him from every direction. While he was doing so, Mustang yanked up his shirt and activated his absorption array. Ed could see the immediate affect it had on him. Harding used the Stone to stop Ed's attack but Ed soon noticed something. The Stone's reaction time was slightly slower. Mustang had resumed his attacks by now but his mind certainly wasn't on the fight.

"Ed, are you okay? What are your injuries?" Mustang asked, concerned.

"I'm fine. The Stone's getting slower though. I think it's running out of souls." Edward ignored the second question. His injuries were nothing major. He had worse, after all. "I think it won't be long before his Stone rebounds." Mustang sent a large fireball at Harding, followed quickly by spears that Ed had obviously created, if the obnoxious style was anything to go by.

"That's great. What are your injuries?" Mustang wasn't easily deterred. Obviously Ed wasn't horribly hurt since he was fighting alongside him however, Mustang was also aware of how ridiculous the kids pain threshold was. Edward sighed to himself. He knew Mustang was a stubborn bastard and just decided to get it over with.

"Nothing major. Couple of broken ribs, a gash in my leg and my shoulder port feels like someone slammed a stone pillar into me." Edward informed him as he tried to make to stone hands squash Harding like a fly, but the arsehole destroyed them. "I'm gonna inform Hotch and the others about the Stone so they know what's happening. Give me cover."

"Hold on, why don't you use your gear they gave you?" Mustang asked, only just remembering the odd gadgets himself.

"Because they broke when I was hit." With that, Ed took off in the direction of the agents, weaving through the various obstacles left by the ongoing fight. He was reminded why he hated broken ribs as he was running over to the agents. He was going to break Harding's ribs and make him run from here to Amestris as payback once this was over. He made it to the agents and held a hand up to stop any oncoming questions.

"Before you ask, I'm totally fine. The Stone's losing power so if you can start taking well aimed shots that force him to use it more, that'd be real handy." Edward explained, wiping a mixture of blood and sweat out of his eyes. "Just try not to hit us, 'kay?" He flashed them a grin as he took off to rejoin Mustang, who was still trying to land a successful blow.

"Damn kid. What does he take us for?" Morgan said as he aimed for Harding and fired off a round which Harding destroyed with the Stone. The other agents followed suit, each firing a round once they had Harding in their cross-hairs. Ed used the distraction the agents offered to create another set of stone hands, this time hoping to simply grab Harding's wrists and force him to drop the Stone. His plan half succeeded. One stone hand managed to snag Harding's right wrist and, judging from the audible snap and yelp of pain, broke his wrist. Edward felt a feral surge of pride run through him at his pain. Ed pounced on Harding's momentary shock from the pain to transmute another stone hand to grab the other wrist but Harding recovered enough to use the Stone to destroy it before it could. But in the same moment, one of the agents fired another round and Mustang sent a stream of fire straight for Harding. Harding managed to deflect the bullet before realising his mistake. He moved a second too late. The fire engulfed him just as he activated the Stone to deflect it. His screams sent shivers up Ed's spine and he kept screaming even after he put the fire out. The only thing holding him in place was Ed's stone hand latched onto his wrist. The rest of him wasn't moving.

"He could be playing possum." Ed hesitantly spoke after a few moments of silence, still poised to launch another attack. "It could be a trap."

"He could be and it could be but I doubt it. That attack landed. And that was one of my stronger attacks. Even extinguishing it as early as he did wouldn't have helped much. He'd still be severely injured." Mustang replied easily, lowering his hand. Edward followed his lead and moved into a relaxed version of his fighting stance. He may trust Mustang's judgement but he knew better to lower his guard until the threat was completely eliminated. That was something he'd learnt the hard way, thanks to his first fight with Envy.

"Why don't you bring him down, Ed? That building-" Mustang was cut off by a sudden flash of redish-purple light suddenly shining from Harding. "What the?" Mustang gasped, bringing his hand back up to snap but Ed stopped him. Mustang looked him. The blonde had dirt and blood streaked across his face and his jacket and shirt was torn in numerous places. But the thing that caught Mustangs immediate attention was his face. His mouth was gaping and eyes were blown wide open with surprise. "What is it, Ed?" It took Ed a couple of tries but eventually he answered.

"It's a rebound, Mustang. The Stone has reached its limit. It's rebounded back on Harding and it looks exactly like the reaction from  _that_  night."


	13. Chapter 13

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

_"It's a rebound, Mustang. The Stone has reached its limit. It's rebounded back on Harding and it looks exactly like the reaction from that night."_

Mustang and the agents could only look in horror as the light show continued for a few more seconds before it abruptly stopped. Everything went quiet. The only things they could hear were the distant city noises and the ominous groans and creaks of the now ruined building as it threatened to cave in on itself. Hotch was the first one to move.

"I'm calling Garcia. We need FDNY out here to help recover his body. That building is too unstable." He said as he pulled out his mobile to do just that when Ed stopped him.

"No, don't call anyone just yet." The blonde was still watching the building with a critical eye.

"Why not? We can't go in there without risking our lives and even I know there's no way for someone to survive that." Hotch argued, finger about to hit Garcia's number.

"Because you could be wrong. He could have survived. I've been privy to rebounds of various magnitudes. I've seen a rebound that massive before and it is survivable. Granted, that rebound wasn't caused by an overused Stone but that's beside the point. Harding very well could have survived and been fused with the Stone. I've seen that before too. Wasn't pretty and the moronic alchemist was even more unstable afterwards. My point is: Harding could be alive and even more pissed off and unstable in there. I don't know who FDNY is but I doubt they're capable of dealing with that." Ed pointed out as he finally tore his gaze from what was left of the rooftop to face the agents.

"I agree with Hotch. There's no way Harding survived that plus the attacks we landed plus collapsing through the roof of the building. There's just no way." Morgan shook his head in disbelief.

"It is possible to survive a rebound that big! I survived one like that! Plus, the roof hasn't caved in yet so he's still up there and he's probably waiting for us to get distracted so he can attack!" Ed snapped, immediately regretting it. He hadn't meant to reveal that bit of his past. Inwardly cursing himself, he continued speaking, hoping they'd forget about what he'd just said. "I'm going to check and see if he's alive and what his status is." He jogged closer to the building, limping slightly, before stopping just before the footpath. Clapping his hands together, he pressed down onto the asphalt before creating a pillar to carry him up level with the building.

Even Hotch didn't say a word as they watched Ed move away after he realised what he'd said. Mustang watched him go with worry barely showing through his well practiced mask.

"Is he serious? He really caused and survived an alchemic rebound like that?" Reid whispered, almost horrified.

"He is. However," Roy held up a hand as Reid opened his mouth again. "I'm not the person you should be asking about it. It's not my story to tell." Reid shut his mouth at the finality in Roy's voice. Roy moved his gaze back to Edward, a silent way of telling the agents to drop the subject, which they did. Ed had now come to a stop, level with the rooftop. He'd produced his automail blade again, just in case Harding had prepared a trap or decided to do what most insane people thought was a great idea, leap from the rooftop to tackle him off his pillar. Ed's golden eyes turned almost clinical as he assessed the scene before him.

Harding was surrounded by a cloud of dust and ash and laying on top of a decent sized pool of blood. He wasn't moving but Ed thought he wouldn't move either if he was in Harding's situation. Harding looked like a half-baked roast. His skin had bubbled and melted in some places, his clothes were barely existent, he had no hair left and that was just from Roy's attack. Ed could see various other wounds; cuts, bullet wounds, broken bones. Taking a deep breath to steady himself, Ed activated his tracking array. While he wasn't using it to track Harding anymore, he had noticed something when he used it to track him from the latest crime scene.  _His tracking array couldn't see anything dead_. He spread his arms and opened his eyes to look at Harding and confirmed his suspicions. Harding was still alive and if his alchemic energy level was true, he was still dangerous. Shutting off his array, Ed almost collapsed from the exhaustion and cursed at this world's lack of alchemic energy. He was so tired that he almost missed the movement on the rooftop and barely managed to dodge the attack Harding had sent towards him. He clapped as he rolled back off the pillar and slammed his hands into the side to create handholds, which he just managed to grab with his automail arm. He almost let go of his handholds as he felt the arm pull at the port from the sudden stop which hurt like bitch still from the blow Harding managed to land earlier, not to mention the sudden stop reminded him very quickly about his broken ribs. He tasted blood as he bit his lip in an effort to stop himself crying out when he felt the port pull at the muscles that grew around it. Dust and chunks of asphalt fell around him, leaving tiny nicks whenever the sharp edges connected with Eds skin as Harding's revitalised attack hit the top part of Eds pillar.

"ED!" He heard several people below him shout as soon as they realised what happened.

"I'm fine!" He shouted back. He gauged his situation and realised he was only a little more than a story high, which he could easily jump from without dying, so he let himself drop and moved into a forward roll as soon as he felt his feet hit the ground, dispersing any momentum he gained. He rolled smoothly onto his feet and was promptly pulled off them again by a very worried and irate Mustang, who was surrounded by the agents, most of whom looked similarly worried.

"What were you thinking? This is why you're always in the hospital! Are you okay? What are your injuries?" Mustang demanded, gripping Ed by his shoulders. Ed hissed as Mustang gripped his shoulder port and moved his shoulder out from Mustangs hand before he bothered answering.

"I don't have any major injuries, Mustang. Seriously," he added as he noticed Mustangs disbelieving expression. "My shoulder port and ribs are the only potentially problematic injuries I've got, I swear."

"What about the gash in your leg?" Mustang asked, knowing that arguing that broken ribs and damaged automail would be a waste of time.

"It's fine. I've suffered worse. And before you start channeling Winry about fighting with damaged automail, I will point out the fact that Truth swore my automail would stay perfectly functional. Which means I can still fight." Ed reminded him. Mustang at least had the decency to look mildly surprised that Ed knew what his train of thought was. Before Mustang could retort, a large shape slammed into the ground, just a few metres behind Ed. Swinging Ed around by his good shoulder so he was facing the threat, Mustang snapped, sending a massive stream of fire straight for Harding, who was currently struggling to get to his feet. Ed decided that Harding didn't look any better up close. It was now obvious how the Stone had rebounded. Harding barely looked human and it had nothing to do with his injuries. His eyes were completely red and his expression was one of a feral animal who'd been tormented, cornered and ready to lash out, consequences be damned. Ed stared at him in fascinated horror. Harding shouldn't have even been able to stand in his condition, let alone willing to fight.

"What happened to him?" JJ's horrified voice whispered to Ed's right. The agents were behind the alchemists but in positions where they could still get a shot off without the two getting hurt. Both alchemists kept their eyes on Harding, analysing his every move to try and predict his next attack.

"That's the result of the rebound we witnessed earlier. He's been forcefully merged with the Stone. My theory? There would've only been a handful of souls left and they probably tried to either take him down with them or merged with him to keep themselves alive a little longer. He is no longer in control. Consider him to be no more than an extremely dangerous animal. He can't be returned to normal now." Edward explained. He wasn't 100% certain what the Stone did but he knew there was no way to fix anything affected by a rebound that big. Harding was going to be delivered to Truth either dead or unconscious and securely bound. "Prepare for anything. He's just going to lash out with random attacks. There'll be no thought process behind his moves, just whatever his instinct says."

"Do you want to try trapping him first?" Mustang asked, hand still poised to snap. Ed considered the question for a moment before answering.

"Yes but not yet. We need to make him use up as much energy as we can so he's easier to trap. I've got a feeling that his senses are a lot sharper now." Ed whispered back at him. Mustang nodded his understanding as Ed turned back to quickly tell the agents that the plan was now to force Harding to use up his energy. Catching Mustang's eye as he turned back to face the front, he nodded, giving the signal to start their newest attack. Ed raced forward, automail blade ready to attack as Mustang skillfully sent controlled bursts of flames at Harding while avoiding Ed. Edward knew that he didn't have a lot of alchemic energy left, even if he were to activate his absorbing array and decided that hand-to-hand was good enough until Harding was exhausted enough to trap. Harding kept dodging Mustang's flames and the agents bullets whenever one of them managed to squeeze off a round but soon had his hands full trying to dodge three various attacks. Ed managed to get in a few good blows before Harding was able to start retaliating. Harding and Ed continued to exchange blows, Harding landing a pretty solid punch directly on Ed's unguarded ribs which had Ed reeling from pain but at the same time, Mustang landed an attack and Morgan's bullet pierced Harding's left thigh, making Harding screech in pain and give Ed a few precious seconds to prepare himself and launch another series of attacks.

As the fight wore on, Ed could feel his own attacks start to become lethargic and sloppy. He was using so much energy that he knew if they didn't end this fight within the next three minutes, Ed would be useless. He hurt all over now thanks to Harding landing more blows than not. He's also acquired lots of cuts and scrapes from having to escape some attacks by throwing himself to the floor. He also had a bullet graze on his flesh arm from one of the agents but he thought it was worth it since that bullet managed to lodge itself in one of Harding's lungs, collapsing it and making it harder for him to fight back. Edward could tell that everyone else was nearly spent. Mustang looked as exhausted as he felt and only Hotch, Rossi and Morgan had bullets left to fire. The other agents had made the executive decision to find some cover since they now couldn't protect themselves. That's when an idea popped into Ed's head. A stupid, reckless idea that might not work but if it did, Harding would never be able to survive it. Mustering up some energy, Ed put some distance between himself and Harding with a couple of back-flips.

"Mustang! Send the biggest fireball you can manage at him! I have a plan!" Ed shouted across the street as he mentally prepared the array he'd need and the energy he had to use. He watched Mustang with an eagle eye. Timing was everything for this plan to succeed. Mustang stilled for a moment before taking a deep breath himself to prepare the energy he'd need to do as Ed requested. Mustang snapped, sending a fireball twice the size of Harding and three times hotter than your average fire straight for Harding. A second later Edward clapped, slamming his hands to the ground in front of him and sending the alchemic energy straight for Harding and the fireball. As he suspected, Harding tried to dodge the fireball but Ed managed to raise a thick wall surrounding him so that he had no choice but to face the oncoming threat. Moments before it landed, Ed completed the array and built a forth wall and roof, trapping Harding and Roy's fireball in the same small space together so that Harding had absolutely no chance of escaping. Harding's screams soon filled the air, screams that made Ed sick to his stomach. After a few moments, the screams died off but nobody made a move towards the makeshift box. After another couple of minutes of absolute silence and waiting for the fire to starve itself, Ed walked up to the wall closest to him before borrowing Scar's trick and destroying the wall. The smell almost made him throw up. His eyes watered and his stomach flipped as he took in the horrific sight of charred remains. A second later, Mustang yanked him away from the sight before rubbing his back soothingly as Edward threw his stomach contents up onto the ground. Shakily wiping his mouth with the back of his gloved hand, Mustang walked him away from the corpse.

Mustang was amazed at Ed's ingenious trap but he also knew that the blonde had never killed someone before. While the smell of burnt flesh and sight of charcoaled remains were not unfamiliar to him, even Mustang struggled with it. He knew that Ed would remain like he was for a little while but what he was really worried about was the fallout. That moment when the blonde realised what had happened. He stood next to Ed, both leaning against one of the cars as the agents moved about, making calls and preserving the scene. His arm was wrapped around the younger mans shoulders as he trembled slightly, a mix of exhaustion and relief. He tightened his grip as he silently vowed to himself that he'd be there for Ed when that fallout happened.


	14. Chapter 14

**Summary for the Chapter:**

> Rather than giving up his alchemy, Ed was offered a deal by Truth. Lose his right arm once more and owe Truth a favour and he could have Alphonse back, whole and healthy. Edward accepts the deal and three months later, Truth collects. An alchemist has managed to dimension travel and is on a murder spree. Truth needs Ed to stop him and Mustang is roped in to helping him. How will the BAU handle having two alchemists literally land in front of them?

It took the agents and local PD most of the day to finish working the crime scene and taking statements. It took a lot of bullshitting on the FBI's and alchemists part to convince the local police that Harding had booby-trapped the area with explosives and other traps and that one of them must've included some sort of accelerate that Harding had gotten on himself and a stray spark from a bullet or bit of flying metal must've set him alight. They even went so far as to caution the police officers and crime scene techs to watch out for any traps that may still be set. Mustang had managed to find Ed's red jacket and hand it back to him so that Ed could hide his automail arm before the locals had shown up. His gloves had been shredded in the fight so Mustang loaned him his, although not before a stern warning and extracting a promise that he would be extra careful with them and that Mustang would get them back as soon as they were back in the hotel or once Ed could get a replacement pair. Ed had grumbled and rolled his eyes but accepted the gloves, making a point to ask if Mustang had hit his head or something because he was starting to act like he cared. While Mustang had only dignified that with a simple 'brat' in response, he was glad to see that Ed had managed to at least put his mask back in place. He was still worried about that moment when everything caught up with him and he realised exactly what had happened but for now he was just happy to see the blonde acting like his normal, bratty self. At one stage, Prentiss and a paramedic had come over to the two and asked if they'd like to go to hospital and the resulting conversation had been very Ed-like; the paramedic had taken one look at Edward covered in blood and grime and strongly recommended the blonde go to a hospital or at least let him look over his injuries. Ed had answered with a simple 'no' and glared at the poor man until he turned his attention to Mustang, only to leave defeated when Mustang had responded with a small shake of his head.

Doctor Reid had managed to come over to them after being questioned and helping with the questioning of a couple of civilians who'd heard the fight and come to check it out (thankfully after it was over) and asked if they'd like to go back to the hotel room and get some food and rest, Edward wasn't the only one to give an enthusiastic 'yes' in response. Reid had chuckled at their reactions and politely asked them to wait a few more minutes while he went and gathered the agents who weren't needed at the scene and would also like food. It turned out that everyone bar Hotch and Rossi accepted the invite for food and sleep and commandeered both cars with JJ promising to come back to pick Hotch and Rossi up when they were finished here. As usual, Ed and Roy traveled in the same car together but this time only with JJ as company. Mustang had seized the opportunity to grab the front seat while Ed was shunted to the back. Edward was honestly too tired to give a shit and the back seat was starting to look more and more like an ideal place for a nap when they started moving. Ed had discovered a while ago that it didn't matter how tired he was, he just couldn't fall asleep in moving cars. It was a talent that both he both hated and loved. The car ride back to the hotel was only broken with questions about what they'd like to eat and when both alchemists had said they didn't mind, JJ had followed up with questions about what foods they liked, didn't like and how hungry they were. Armed with the knowledge that if milk, unless in cheese form, or any capsicum or peas made an appearance in any of their food, the agents would have two severely displeased alchemists on their hands, she dropped them off at the hotel and gathered orders from the other agents. As she pulled away in search of a restaurant that could prepare enough food to feed an army and to fill Garcia in, the rest of the group headed into the hotel room. There was a small discussion about whether they'd be eating in their own rooms or altogether in the meeting room Ed had discovered. Morgan was the one who had made the decision in the end. He pointed out that Ed looked dead on his feet and that Mustang didn't look much better and since they didn't know how long JJ was going to be, they might as well head to their rooms and get some sleep until she did come back. After being assured that someone would get them for food, both alchemists disappeared into their room. Almost immediately, Ed was in the shower. Mustang scrounged around their room and found a small first aid kit in their little kitchenette. Within minutes, Ed exited the bathroom wearing only his boxers and carrying the rest of his clothes and a small first aid kit he'd found in the bathroom. Mustang seized the opportunity to really give him a proper look over, noting every injury he found.

"I'm going for a shower. Don't go to sleep yet. I'll help you treat those wounds." Mustang ordered as he walked away. Edward barely managed an eye roll in response. Quickly undressing and hopping in the shower, Mustang scrubbed himself clean and did his own wound inventory. He'd suffered cuts, grazes, bruises and sprained wrist from when Edward had tackled him to the ground but only one cut seemed like it'd need stitches. The rest could be left alone to heal. Finishing his shower, he walked out dressed the same as Ed. Edward didn't even flinch when Mustang walked out of the bathroom. He had a kit opened next to him on the bed and was currently cleaning one of the many cuts he'd received.

"Put your clothes over there with mine." Ed said, not even looking up as he pointed to his bundle of filthy clothes. "I'll clean and mend them after we get some sleep." Mustang did as directed and made himself comfortable on the bed next to the blonde. Edward didn't even protest when Mustang gently lifted his arm and took the alcohol-covered swap from him and continued disinfecting the wounds. Mustang noted that only a couple of the cuts Ed had sustained on his upper half would need stitches. He tossed the swab in the bin, prepared a new one and move onto the head wound Ed had gotten. He knelt in front of Ed for this one, using one hand to keep Ed's bangs out of his eyes while he gently cleaned the gash. Ed winced in pain but otherwise showed no signs of discomfort. While the wound had bled heavily during the fight, it wouldn't require stitching. Just some gauze and a bandage to protect it from reopening. Switching out the swabs again, Mustang moved onto Ed's legs. His left hadn't sustained any injuries, aside from some minor bruising but he had a particularly nasty gash on the right calf.

"This one's going to hurt like a bitch to clean. I'm going to have to get in there properly to clean it." Mustang warned Ed.

"I've had worse. Just do it." Was all Ed responded with. So Mustang did as he asked. Ed flinched when Mustang started but the older alchemist simply held his leg still and continued with his work.

"Did you notice if there were any supplies for stitching in the kits?" Mustang asked as he finished up with the gash. Once it had been cleaned out and he'd gotten a proper look at it, Mustang realised that it wasn't as deep as he'd originally thought. It definitely needed stitches but he'd been worried that he'd have to drag the blonde to a hospital to get it dealt with. Thankfully, he got to avoid knocking the kid out and dealing with the angry aftermath.

"No, there weren't. What kind of med kit doesn't have crap for stitches?" Ed grouched.

"Clearly they weren't prepared for you and your knack for getting seriously injured." Mustang smoothly replied as he rummaged through the kit looking for things he could use.

"Oh, shut it, Mustang. Are you nearly done?" Ed snapped at him. Mustang made a small sound of victory when he came up with a trauma pad and some more bandages.

"Nearly. I've just gotta wrap your leg up and you'll be right until we get back to Amestris to get that leg and arm stitched up." He answered as he proceeded to wrap said wound up. Once he was finished, he cleaned up the empty wrappings and used disinfectant swaps and tossed them. While he was doing that, Ed inspected his handiwork and had to silently admit that Mustang had done a decent job. Ed watched the older alchemist sit himself on his bed and start pilfering supplies from the second kit. He could tell from the way the man was holding his arm that his wrist was damaged. Sighing, the blonde stood and limped over to the other man before sitting heavily next to him and pinching the swabs he'd grabbed.

"What are you doing?" Mustang asked, startled.

"What does it look like? Helping." Edward replied as he set to work. He may not have had medical training provided for him but he'd hurt and patched himself up enough times to know the basics.

"You should be resting. I can manage by myself." Mustang argued as he reached to take the swab back.

"You've got a busted wrist, injured shoulder and a decent scratch on your back. There's no way you can clean it out properly, even if that was your only injury." Ed pointed out as he moved his hand to dodge Mustang's grab. Mustang froze.

"I do?" He asked, confused. He never noticed he'd injured his back when he was in the bathroom but now that Ed had mentioned it, his shoulder blades were throbbing.

"See? You obviously need help if you didn't even notice that." Mustang had to agree with that so he let Ed clean him up. He was a bit worried by the fact that Ed seemed too at ease with what he was doing. Ed finished cleaning his shoulder wound and put a small gauze over it and wrapped it up nicely.

"Turn around, Mustang." Ed requested. Roy complied and winced as he felt Ed clean out his back wound.

"I guess it's an unfounded hope that you learnt to do this simply because you read a medical book?" Mustang queried. Ed let out a small huff of amusement.

"Of course I read medical text books. But there's nothing like a bit of real world practise to make sure you know what you're doing." Ed replied as he finished up Mustangs back. Thankfully it was a shallow wound. It wouldn't even need wrapping up. "You can turn back around now. Gimme your wrist." Mustang did as he was told and held out his injured wrist.

"Do I even want to know?" Mustang asked as Ed gently prodded his wrist and hand to judge the severity of the injury.

"Let's just say that my medical history contains barely half of my injuries. It's just a bad sprain, by the way. So you'll need to ice it and rest it for a few days. Luckily, it's not your writing hand so you'll be able to get back to all that wonderful paperwork once we go home." Ed grinned as he started wrapping Mustangs wrist up. Mustang groaned at the thought of going back to nearly a weeks worth of paperwork and a very pissed off Lieutenant. Ed hid an amused smile as he finished what he was doing and cleaned up. Mustang stood and moved to the fridge to check for any ice packs or ice he could wrap up. Thankfully, he found an ice pack and placed it over his wrist as he headed back to his bed. He had thought he'd see the blonde curled up, fast asleep but was surprised to see him drawing on himself. Glancing at it, he recognised the absorbing array just as Ed finished drawing it. Edward looked up and saw Mustang standing next to him, looking down at the array. He motioned for him to hold out his arm.

"Activate it before you go to sleep. That way we can speed up our intake of energy while we rest." Edward told him as he traced the array onto Mustangs arm. Mustang nodded at the words. "Done. Get some sleep, Mustang. You look like shit." Edward said with a small wave of his hand. Mustang snorted but did as he was told. He got himself under his blankets and watched Ed do the same, albeit a bit more cautiously thanks to his wounds. Both alchemists got settled and activated their arrays, immediately feeling the effects. Roy was nearly asleep when he heard his name.

"Hey, Mustang?"

"Yes, Ed?"

"Thanks for helping me."

"Anytime, kiddo. Thanks for helping me."

"Anytime, old man."

"I'M NOT OLD!" The last thing Mustang heard before he fell asleep was Ed's laughter and he had to admit, there were worse sounds to fall asleep too.

* * *

 

Ed had hoped that his exhaustion would lead to a dreamless sleep, only to be confronted with something he hated more than his nightmares. A white world and a black gate.

"Hello, young alchemist." The static figure grinned at him.

"Hello, Truth." Edward sighed. "What do you want?"

"Why, Edward. What could I possibly want with you except to congratulate you on a job well done?" Truth asked, sounding almost affronted.

"If we've finished the job, are you here to bring me and Mustang back?" Edward asked.

"Not quite. You see, I can't bring you back unless you activate the human transmutation circle and come here yourselves." Truth grinned. A trickle of suspicion tickled the back of Ed's mind.

"Will there be a price to pay if we do that?" Edward asked, 70% sure of the answer.

"Of course! You don't expect to pass through me  _twice_  without payment?" Truth asked.

"Of course you'd make us pay for the return trip. Why isn't included as part of the deal? We succeeded in our mission so why isn't that payment enough?" Ed demanded.

"Our deal was that you would owe me a favour in exchange for your brother back, body and soul. I called in that favour when Harding managed to sneak past me. Our deal was that you and Roy would stop Harding and that I would give you passage through the Gate, information pertaining to that world and keep your automail and alchemy functional. A free return trip was not discussed and therefore isn't part of the deal. You need to pay a toll to get back to Amestris." Truth explained, as though it was obvious. Edward simply stared at it, mouth slightly agape.

"You're serious?" Was all he managed to gasp out as he felt Truth's words sink in. "You're seriously making us pay to get home?"

"Of course! Equivalent exchange, young alchemist! You completed you task thus your payment for your brothers return has been finalised. I owe you no favours after all. I'm sending you back now. It seems the lovely Miss JJ is knocking at your door. See you soon, Edward." Truth's evil grin was the last thing he saw before his eyes snapped open and he woke gasping for breath.

"Edward! Are you okay?" Mustang was hovering next to him as he fought to calm his breathing down. He could vaguely hear knocking in the background. Finally, he managed to get his breathing under control as he sat up.

"I'm fine. Go and get the door before they break it down. I'll tell you about it later." He got carefully out of bed and grabbed their dirty clothes, ignoring Mustang staring at him. As he clapped his hands to perform his cleaning array, Mustang moved towards the door to answer it. Murmured voices were heard and a minute later the door shut and Mustang was back next to Ed.

"It was Agent Jareau. Food's here and we're all gathering in that meeting room in five minutes. What happened? Another nightmare?" Obviously, Mustang wasn't going to be easily dissuaded. Ed handed him his clean and mended clothing, which Mustang accepted with a thanks but didn't make a move to put on, waiting patiently for Ed to talk. Sighing, Ed clapped and performed the same cleaning and mending arrays on his own clothes.

"It wasn't a nightmare. Truth paid me a visit." Ed said in a flat voice as he started to dress himself, being mindful of his injuries. Mustang started following his lead.

"What did it want?" Mustang queried, knowing it wasn't going to be good news, judging by Edwards expression.

"It decided to tell us we did a good job stopping Harding and to inform me that we aren't going back to Amestris unless we pay a price." Edward informed him. Mustang froze, halfway through buttoning up his shirt.

"Are you serious? It's making us pay for passage back?" Mustang sounded disbelieving and disgusted.

"Yeah. Apparently, passage back wasn't part of our deal. I'm sorry, Mustang." Edward hung his head.

"Why are you apologising? It's that bastards fault!" Mustang asked, gripping Ed by his shoulders and making him look up.

"I didn't think about the return trip and now we have to pay Truth knows what to get home! You shouldn't have even been here. It was a deal between me and Truth. You had nothing to do with it and now you have to pay for it!" Edward blamed his exhaustion and the events of the past few days on the fact that his eyes were starting to fill with tears. Mustang noticed and felt his heart ache at the sight.

"Listen to me, Ed. None of this is your fault." Ed opened his mouth to argue but Mustang cut him off. "No, listen. Truth offered to send me back before we got sent here, remember?" A slow nod answered him. "I chose to come with you. While you're very talented at defying the odds, your chances of surviving this mission were apparently increased by me being here. So I decided that I'd come with you and make sure you got back to your brother in one piece. I do not regret my decision and I will pay my toll to pass through the Gate if that's what I need to do to make sure you get back to Al. In no way is this your fault. If you wanna blame something, blame me for agreeing to go or blame Truth for being an arsehole. Okay?" A small, slightly watery chuckle escaped Ed as Mustang finished.

"Okay." Edward said as he rubbed his eyes with the heel of his flesh hand.

"Good. Now, did you manage to transmute yourself some gloves or do you want to continue borrowing mine?" Mustang asked as he removed his hands from Ed's shoulders and noticing the lack of gloves on either of them. Ed picked up the gloves from the table the clothes had been on and handed them back to Mustang.

"I'm good, I transmuted a pair before." He said as he pulled said gloves on, Mustang mimicking his actions.

"Excellent. Now, let's go get something to eat and get back up here so we can get some more sleep before we figure out what we're going to do about Truth." Mustang declared as he ushered Edward out the door and down towards food. Ed laughed at his antics but went along willingly. Very little could upset the blonde enough to put him off food and Truth wasn't one of them. Ed led the way down and subsequently was first through the door. Which meant he was the first to be tackled by a blonde launching herself at him. He winced in pain as the bear hug put pressure on his busted ribs before the blonde was gone as quickly as she came. She hadn't gone far and soon Mustang was captured in her embrace. Garcia finally calmed down enough to notice that her new friends were injured and soon the alchemists were fighting off apologies. Morgan soon intervened and led Garcia away from them so they could find a place to sit at the table. The aroma of the assortment of food was making both them salivate. They barely noticed that Hotch and Rossi were also present. They sat politely at the table and waited patiently for everyone else to be seated. Edward was ready to just launch himself at the food and start shoveling it in his mouth at top speed but he restrained himself. The fact that Mustang hand one arm gripping his flesh arm to hold him back also helped. Soon enough, everyone was helping themselves to the food. Ed and Roy had next to no idea what they were eating. Some of it was pizza, some of it tasted kinda like Cretan food, some tasted similar to Xingian food but right now they were more focused on eating than what they were eating. Twenty minutes and several empty food containers in front of them later, Edward and Roy had finally eaten their fill, much to the amusement of the agents, all of whom had finished eating a while back. There was some idle chatter among everyone, mostly the agents and alchemists answering questions about the battle for Garcia. Once Garcia had run out of questions, Hotch spoke up.

"I understand that you joined forces with us solely because he was one of your people but I wanted to thank both of you for your assistance in putting a stop to Harding's killing spree. After witnessing the fight between the three of you, I have to admit that we'd have been hardpressed going up against him without you. So thank you."

"It was our duty to stop him but we couldn't have done it without your help. Not only would we have been struggling to understand your country but we more than likely wouldn't have caught up to him until he'd killed more people. Without your assistance and acceptance of us, we wouldn't have stopped him so quickly. There's no need to thank us." Mustang replied while Ed stopped himself rolling his eyes at how diplomatic these two were being.

"Yeah, like Mustang said. We'd have been fucked finding our way round this place by ourselves so no need to thank us. We also kinda killed your mics and whatever techy things you gave us during the fight so you definitely don't have to thank us. Also, I killed that tracking device you'd hidden in my jacket pocket." Ed said as he raised his eyebrow at Hotch and handed over the destroyed device. Hotch took it with a small chuckle.

"So you found that, huh?" Ed laughed at Mustangs surprised face.

"Yeah. Good try but next time, slip it into my right pocket. Probably wouldn't have found it so quick with the hand I can't feel." Ed helpfully told him.

"You were tracking us?" Mustang demanded. Ed put a hand on his arm.

"Chill, Mustang. Like you wouldn't have done the same thing. They were just taking precautions." Ed logically pointed out, making Mustang deflate a bit.

"Now that that's been dealt with, there is something else I'd like to discuss with you. I think you'd be very interested." Hotch said once Mustang had sat back down. Edward raised an eyebrow and Hotch took the hint. "Rossi and I were helping the local PD sweep the area Harding was hiding in for any more 'booby traps' when we found something that you might want to take back home with you." He said as he reached into his pocket and pulled out a white cloth folded in half. Unwrapping it, he revealed two small red stones.

"No fucking way." Ed could only say as he realised what he was looking at. Mustangs jaw was hanging open and he looked as shocked as Ed felt. "He had more Stones?!"

"It would appear so. We found them in his hideout, tucked away in a small hole in the wall. Honestly, if we hadn't heard you describe them, we wouldn't have paid much attention to them. Since they're of your world and pose a danger here, Rossi and I decided to give them back to you to deal with as you see fit." He explained as he handed them Edward, who took them cautiously, like he was being handed an unstable bomb.

"Ed, you realise what this means, right?" Mustang asked as soon as he got over his shock.

"Yeah. It means we got fucking lucky that Harding couldn't get back to his hideout and get these." Ed said as he felt the slight hum of power going through him, thanks to the Stone.

"No, well, yes but not just that. We have our payment for Truth." Ed whipped his head to look at him with surprise. "We can use these to buy our way back." Ed grinned as Mustangs words sunk in.

"What do you mean 'buy your way back'?" Reid asked, snapping the alchemists attention back to their forgotten audience. Both exchanged a glance before apparently coming to a silent agreement,

"I had a visit from Truth. I'm pretty sure I explained who it is when we first arrived, right?" The agents all nodded. "Well, it spoke to me and informed that while we had completed the mission, we had to pay our way back since it was apparently not included in the deal. We were going to go back to the room and discuss what to do but now that we have these, we can exchange them for our trip back." Ed explained, still looking slightly perplexed that they got the Stones.

"You have to pay? Like, money?" Garcia asked. Ed chuckled darkly.

"Not quite. You pay whatever Truth deems a fair price in exchange for what you want. The first time I went through the Gate, it cost me my leg. The second time, my arm." Edward said. Most of the agents gasped while the others just looked like they were in shock.

"You went through it a second time? Even though you'd already lost your leg?" Morgan asked disbelievingly.

"The first time, I didn't understand what I'd done or the price I paid. The second time, I didn't know what price I was going to pay but I had to go back through. It was the only way to save my brother." Edward said curtly. Feeling the tension in the air, JJ changed the topic slightly.

"So when are you going to head back?" She asked, a little sad at the prospect of saying goodbye so soon. She really enjoyed having them around.

"Now that we've got the Stones, we can head back at anytime." Ed said. "The sooner, the better. I've got a little brother to get back to and Mustangs got some paperwork to start catching up on." He added with a smirk.

"Maybe we can stay here a few more days." Mustang suggested halfheartedly. Ed wasn't the only one to laugh.

"That just means more paperwork and a very pissed Lieutenant when she finds out that you bludged here for a few more days to avoid paperwork." Ed pointed out. Mustang sighed and accepted defeat. "Do you know what the array looks like or do you want me to draw it?" Ed asked.

"Draw it out. I only remember the one you drew and I'm not confident I remember it 100%." Mustang said after much deliberation. Edward nodded and complied. Pulling out his stolen marker, he drew the array out on the table. Once finished, they both turned towards the agents.

"Destroy this as soon as we leave, please." Edward asked Hotch, who nodded solemnly. "Thanks again for everything, especially the food." Ed said, gaining a small chuckle from the agents. Garcia and JJ both gave him and Mustang hugs while everyone else settled for a slap on the back or handshake as goodbyes.

"It was fantastic meeting you both and I almost hope we get to meet you again." Reid said, grinning at Ed.

"Ditto, Doc." Ed grinned back before he and Mustang waved one final time and placed both hands on the array, activating it. A huge flash of blue light soon turned purple and both alchemists soon vanished, leaving only the array behind. JJ sighed as she left to go request some cleaning supplies from the front desk clerk so they could fulfill their final promise to the alchemists.

* * *

 

Meanwhile, Ed and Roy stood in a familiar expanse of white, facing Truth.

"Welcome back, alchemists."

"We're here to go home." Ed didn't bother with pretending to be polite.

"Oh? And what do you plan to pay with?" Truth grinned.

"These." Mustang said as both he and Edward held out their hands, revealing the two Philosopher's Stones. Truth's grin grew wider.

"Oooh. A very handsome payment indeed." Truth cooed as it reached out to take the Stones. Seemingly inspecting them, it finally turned its attention back to Ed and Roy. "Very well. I accept your payments. You're free to go home." It told them as the Gate's doors opened wide and familiar black hands grabbed them to drag them through. The last glimpse they'd ever get of Truth was of it grinning at them, waving them goodbye before they blacked out.

* * *

 

When they came to, is was on a pristine white floor and to the sounds of two panicked voices calling their names.

"Chief! Boss!"

"Colonel! Brother!"

Mustang and Ed both slowly sat up and took in their surroundings. They were back in Amestris, specifically Al's hospital room in Central Hospital. They met each others eyes and grinned. It had worked, they were both home and in one piece. Ed felt a hand on his flesh arm help him stand while Mustang helped himself up. Soon, Ed was yanked away from Havoc's grip and down onto Al's bed where he then subjected to a hug stronger than Garcia's.

"Where have you two been?!" Al half-shouted through sobs. "You've been missing for five days! I've been worried sick!" Ed soothingly rubbed Al's back as the younger blonde sobbed onto his shoulder. It took a little while for him to calm down, time that Mustang had Havoc to use during and soon Ed was seated on Al's bed while Mustang took over Ed's usual chair and they faced a relieved and seriously angry Lieutenant Hawkeye and a relieved and terrified looking crew.

"So? Are you going to tell us what was so important that you disappeared without telling anyone, only to come back injured?" Hawkeye demanded. Edward and Mustang grinned.

"It's a long story so you better get comfy."

**Notes for the Chapter:**

> So this was my first FMA crossover I ever wrote and I can't believe how well it has been received here! I want to thank everyone who read it and took the time to comment or leave a kudos. It really meant a lot to me. There is a sequel, which I will start posting tomorrow. Like this story, it is complete so updates will be every few days for it as well. Thank you for all the love you've shown this work, once again, and I'll see you next time!


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